diff --git a/boot/boot.js b/boot/boot.js
index df89561d46a..058e0f685fc 100644
--- a/boot/boot.js
+++ b/boot/boot.js
@@ -14,6 +14,8 @@ var _boot = (function($tw) {
 
 "use strict";
 
+if(typeof performance !== "undefined") { performance.mark("tw-boot-start"); }
+
 // Include bootprefix if we're not given module data
 if(!$tw) {
 	$tw = require("./bootprefix.js").bootprefix();
@@ -1158,6 +1160,30 @@ $tw.Wiki = function(options) {
 		pluginTiddlers = [], // Array of tiddlers containing registered plugins, ordered by priority
 		pluginInfo = Object.create(null), // Hashmap of parsed plugin content
 		shadowTiddlers = Object.create(null), // Hashmap by title of {source:, tiddler:}
+		systemTiddlerTitles = null, // Array of system tiddler titles (starting with "$:/")
+		nonSystemTiddlerTitles = null, // Array of non-system tiddler titles
+		partitionTiddlerTitles = function() {
+			if(systemTiddlerTitles === null) {
+				systemTiddlerTitles = [];
+				nonSystemTiddlerTitles = [];
+				var titles = getTiddlerTitles();
+				for(var i = 0, length = titles.length; i < length; i++) {
+					if(titles[i].indexOf("$:/") === 0) {
+						systemTiddlerTitles.push(titles[i]);
+					} else {
+						nonSystemTiddlerTitles.push(titles[i]);
+					}
+				}
+			}
+		},
+		getSystemTiddlerTitles = function() {
+			partitionTiddlerTitles();
+			return systemTiddlerTitles;
+		},
+		getNonSystemTiddlerTitles = function() {
+			partitionTiddlerTitles();
+			return nonSystemTiddlerTitles;
+		},
 		shadowTiddlerTitles = null,
 		getShadowTiddlerTitles = function() {
 			if(!shadowTiddlerTitles) {
@@ -1206,6 +1232,14 @@ $tw.Wiki = function(options) {
 				tiddlers[title] = tiddler;
 				// Check we've got the title
 				tiddlerTitles = $tw.utils.insertSortedArray(tiddlerTitles || [],title);
+				// Maintain system/non-system partitions
+				if(systemTiddlerTitles !== null) {
+					if(title.indexOf("$:/") === 0) {
+						$tw.utils.insertSortedArray(systemTiddlerTitles,title);
+					} else {
+						$tw.utils.insertSortedArray(nonSystemTiddlerTitles,title);
+					}
+				}
 				// Record the new tiddler state
 				updateDescriptor["new"] = {
 					tiddler: tiddler,
@@ -1246,6 +1280,14 @@ $tw.Wiki = function(options) {
 					tiddlerTitles.splice(index,1);
 				}
 			}
+			// Delete from system/non-system partitions
+			if(systemTiddlerTitles !== null) {
+				var partitionArray = title.indexOf("$:/") === 0 ? systemTiddlerTitles : nonSystemTiddlerTitles;
+				var partitionIndex = partitionArray.indexOf(title);
+				if(partitionIndex !== -1) {
+					partitionArray.splice(partitionIndex,1);
+				}
+			}
 			// Record the new tiddler state
 			updateDescriptor["new"] = {
 				tiddler: this.getTiddler(title),
@@ -1284,6 +1326,16 @@ $tw.Wiki = function(options) {
 		return getTiddlerTitles().slice(0);
 	};
 
+	// Get an array of all system tiddler titles (returns cached array; do not mutate)
+	this.allSystemTitles = function() {
+		return getSystemTiddlerTitles();
+	};
+
+	// Get an array of all non-system tiddler titles (returns cached array; do not mutate)
+	this.allNonSystemTitles = function() {
+		return getNonSystemTiddlerTitles();
+	};
+
 	// Iterate through all tiddler titles
 	this.each = function(callback) {
 		var titles = getTiddlerTitles(),
@@ -2539,7 +2591,9 @@ $tw.boot.loadStartup = function(options){
 
 	// Load tiddlers
 	if($tw.boot.tasks.readBrowserTiddlers) {
+		if(typeof performance !== "undefined") { performance.mark("tw-boot-store-read-start"); }
 		$tw.loadTiddlersBrowser();
+		if(typeof performance !== "undefined") { performance.mark("tw-boot-store-read-end"); }
 	} else {
 		$tw.loadTiddlersNode();
 	}
@@ -2551,6 +2605,7 @@ $tw.boot.loadStartup = function(options){
 	$tw.hooks.invokeHook("th-boot-tiddlers-loaded");
 };
 $tw.boot.execStartup = function(options){
+	if(typeof performance !== "undefined") { performance.mark("tw-boot-exec-start"); }
 	// Unpack plugin tiddlers
 	$tw.wiki.readPluginInfo();
 	$tw.wiki.registerPluginTiddlers("plugin",$tw.safeMode ? ["$:/core"] : undefined);
@@ -2578,6 +2633,7 @@ $tw.boot.execStartup = function(options){
 	$tw.boot.executedStartupModules = Object.create(null);
 	$tw.boot.disabledStartupModules = $tw.boot.disabledStartupModules || [];
 	// Repeatedly execute the next eligible task
+	if(typeof performance !== "undefined") { performance.mark("tw-boot-startup-modules-start"); }
 	$tw.boot.executeNextStartupTask(options.callback);
 };
 /*
@@ -2645,6 +2701,7 @@ $tw.boot.executeNextStartupTask = function(callback) {
 		}
 		taskIndex++;
 	}
+	if(typeof performance !== "undefined") { performance.mark("tw-boot-complete"); }
 	if(typeof callback === "function") {
 		callback();
 	}
diff --git a/boot/bootprefix.js b/boot/bootprefix.js
index c4ebc617275..42e751901e8 100644
--- a/boot/bootprefix.js
+++ b/boot/bootprefix.js
@@ -14,6 +14,8 @@ See Boot.js for further details of the boot process.
 
 /* eslint-disable @stylistic/indent */
 
+if(typeof performance !== "undefined") { performance.mark("tw-bootprefix-start"); }
+
 var _bootprefix = (function($tw) {
 
 "use strict";
@@ -23,7 +25,7 @@ $tw.boot = $tw.boot || Object.create(null);
 
 // Config
 $tw.config = $tw.config || Object.create(null);
-$tw.config.maxEditFileSize = 100 * 1024 * 1024; // 100MB
+$tw.config.maxEditFileSize = 200 * 1024 * 1024; // 200MB
 
 // Detect platforms
 if(!("browser" in $tw)) {
@@ -121,6 +123,7 @@ return $tw;
 if(typeof(exports) === "undefined") {
 	// Set up $tw global for the browser
 	window.$tw = _bootprefix(window.$tw);
+	if(typeof performance !== "undefined") { performance.mark("tw-bootprefix-end"); }
 } else {
 	// Export functionality as a module
 	exports.bootprefix = _bootprefix;
diff --git a/core/modules/filters.js b/core/modules/filters.js
index 2cfa60914ec..17ea80ecdee 100644
--- a/core/modules/filters.js
+++ b/core/modules/filters.js
@@ -261,6 +261,7 @@ exports.compileFilter = function(filterString) {
 	var filterOperators = this.getFilterOperators();
 	// Assemble array of functions, one for each operation
 	var operationFunctions = [];
+	var operationSubFunctions = []; // Unwrapped sub-functions for fast path
 	// Step through the operations
 	var self = this;
 	$tw.utils.each(filterParseTree,function(operation) {
@@ -289,20 +290,24 @@ exports.compileFilter = function(filterString) {
 						operand.value = self.getTextReference(operand.text,"",currTiddlerTitle);
 						operand.multiValue = [operand.value];
 					} else if(operand.variable) {
-						var varTree = $tw.utils.parseFilterVariable(operand.text);
-						operand.value = widgetClass.evaluateVariable(widget,varTree.name,{params: varTree.params, source: source})[0] || "";
+						if(!operand._varTree) {
+							operand._varTree = $tw.utils.parseFilterVariable(operand.text);
+						}
+						operand.value = widgetClass.evaluateVariable(widget,operand._varTree.name,{params: operand._varTree.params, source: source})[0] || "";
 						operand.multiValue = [operand.value];
 					} else if(operand.multiValuedVariable) {
-						var varTree = $tw.utils.parseFilterVariable(operand.text);
-						var resultList = widgetClass.evaluateVariable(widget,varTree.name,{params: varTree.params, source: source});
+						if(!operand._varTree) {
+							operand._varTree = $tw.utils.parseFilterVariable(operand.text);
+						}
+						var resultList = widgetClass.evaluateVariable(widget,operand._varTree.name,{params: operand._varTree.params, source: source});
 						if((resultList.length > 0 && resultList[0] !== undefined) || resultList.length === 0) {
-							operand.multiValue = widgetClass.evaluateVariable(widget,varTree.name,{params: varTree.params, source: source}) || [];
+							operand.multiValue = widgetClass.evaluateVariable(widget,operand._varTree.name,{params: operand._varTree.params, source: source}) || [];
 							operand.value = operand.multiValue[0] || "";
 						} else {
 							operand.value = "";
 							operand.multiValue = [];
 						}
-						operand.isMultiValueOperand = true;	
+						operand.isMultiValueOperand = true;
 					} else {
 						operand.value = operand.text;
 						operand.multiValue = [operand.value];
@@ -343,6 +348,7 @@ exports.compileFilter = function(filterString) {
 				return resultArray;
 			}
 		};
+		operationSubFunctions.push(operationSubFunction);
 		var filterRunPrefixes = self.getFilterRunPrefixes();
 		// Wrap the operator functions in a wrapper function that depends on the prefix
 		operationFunctions.push((function() {
@@ -372,6 +378,10 @@ exports.compileFilter = function(filterString) {
 			}
 		})());
 	});
+	// Detect single "or" run for fast path (bypass LinkedList)
+	var isSingleOrRun = filterParseTree.length === 1 &&
+		(!filterParseTree[0].prefix || filterParseTree[0].prefix === "");
+	var singleOrSubFunction = isSingleOrRun ? operationSubFunctions[0] : null;
 	// Return a function that applies the operations to a source iterator of tiddler titles
 	var fnMeasured = $tw.perf.measure("filter: " + filterString,function filterFunction(source,widget) {
 		if(!source) {
@@ -382,23 +392,30 @@ exports.compileFilter = function(filterString) {
 		if(!widget) {
 			widget = $tw.rootWidget;
 		}
-		var results = new $tw.utils.LinkedList();
 		self.filterRecursionCount = (self.filterRecursionCount || 0) + 1;
+		var resultArray;
 		if(self.filterRecursionCount < MAX_FILTER_DEPTH) {
-			$tw.utils.each(operationFunctions,function(operationFunction) {
-				var operationResult = operationFunction(results,source,widget);
-				if(operationResult) {
-					if(operationResult.variables) {
-						// If the filter run prefix has returned variables, create a new fake widget with those variables
-						widget = widget.makeFakeWidgetWithVariables(operationResult.variables);
+			if(singleOrSubFunction) {
+				// Fast path: single "or" run, return array directly without LinkedList
+				resultArray = singleOrSubFunction(source,widget);
+			} else {
+				var results = new $tw.utils.LinkedList();
+				$tw.utils.each(operationFunctions,function(operationFunction) {
+					var operationResult = operationFunction(results,source,widget);
+					if(operationResult) {
+						if(operationResult.variables) {
+							// If the filter run prefix has returned variables, create a new fake widget with those variables
+							widget = widget.makeFakeWidgetWithVariables(operationResult.variables);
+						}
 					}
-				}
-			});
+				});
+				resultArray = results.toArray();
+			}
 		} else {
-			results.push("/**-- Excessive filter recursion --**/");
+			resultArray = ["/**-- Excessive filter recursion --**/"];
 		}
 		self.filterRecursionCount = self.filterRecursionCount - 1;
-		return results.toArray();
+		return resultArray;
 	});
 	if(this.filterCacheCount >= 2000) {
 		// To prevent memory leak, we maintain an upper limit for cache size.
diff --git a/core/modules/filters/is/shadow.js b/core/modules/filters/is/shadow.js
index 4f1335c692b..b379ab44e1e 100644
--- a/core/modules/filters/is/shadow.js
+++ b/core/modules/filters/is/shadow.js
@@ -13,6 +13,18 @@ Filter function for [is[shadow]]
 Export our filter function
 */
 exports.shadow = function(source,prefix,options) {
+	// Fast path: when source is wiki.each (all real tiddlers), use shadow title list
+	if(source === options.wiki.each && prefix !== "!") {
+		// Return real tiddlers that are also shadow tiddlers (overridden shadows)
+		var results = [],
+			shadowTitles = options.wiki.allShadowTitles();
+		for(var i = 0, len = shadowTitles.length; i < len; i++) {
+			if(options.wiki.tiddlerExists(shadowTitles[i])) {
+				results.push(shadowTitles[i]);
+			}
+		}
+		return results;
+	}
 	var results = [];
 	if(prefix === "!") {
 		source(function(tiddler,title) {
diff --git a/core/modules/filters/is/system.js b/core/modules/filters/is/system.js
index b27feb3923e..ad6f52b7770 100644
--- a/core/modules/filters/is/system.js
+++ b/core/modules/filters/is/system.js
@@ -13,6 +13,14 @@ Filter function for [is[system]]
 Export our filter function
 */
 exports.system = function(source,prefix,options) {
+	// Fast path: when iterating all tiddlers, use pre-partitioned arrays
+	if(source === options.wiki.each) {
+		if(prefix === "!") {
+			return options.wiki.allNonSystemTitles();
+		} else {
+			return options.wiki.allSystemTitles();
+		}
+	}
 	var results = [];
 	if(prefix === "!") {
 		source(function(tiddler,title) {
diff --git a/core/modules/filters/is/tiddler.js b/core/modules/filters/is/tiddler.js
index 24ca5cee29e..36cdc587018 100644
--- a/core/modules/filters/is/tiddler.js
+++ b/core/modules/filters/is/tiddler.js
@@ -13,6 +13,13 @@ Filter function for [is[tiddler]]
 Export our filter function
 */
 exports.tiddler = function(source,prefix,options) {
+	// Fast path: wiki.each only iterates real tiddlers, all of which exist
+	if(source === options.wiki.each) {
+		if(prefix === "!") {
+			return []; // No real tiddler fails tiddlerExists
+		}
+		return source; // Return iterator directly; all real tiddlers pass
+	}
 	var results = [];
 	if(prefix === "!") {
 		source(function(tiddler,title) {
diff --git a/core/modules/filters/tags.js b/core/modules/filters/tags.js
index c4ce719c8c6..006670ee5f3 100644
--- a/core/modules/filters/tags.js
+++ b/core/modules/filters/tags.js
@@ -13,6 +13,21 @@ Filter operator returning all the tags of the selected tiddlers
 Export our filter function
 */
 exports.tags = function(source,operator,options) {
+	// Fast path: cache result when iterating all tiddlers
+	if(source === options.wiki.each) {
+		return options.wiki.getGlobalCache("filter-tags-all-tiddlers",function() {
+			var tags = {};
+			source(function(tiddler,title) {
+				var t, length;
+				if(tiddler && tiddler.fields.tags) {
+					for(t=0, length=tiddler.fields.tags.length; t<length; t++) {
+						tags[tiddler.fields.tags[t]] = true;
+					}
+				}
+			});
+			return Object.keys(tags);
+		});
+	}
 	var tags = {};
 	source(function(tiddler,title) {
 		var t, length;
diff --git a/core/modules/indexers/tag-indexer.js b/core/modules/indexers/tag-indexer.js
index 7844173c634..63993dcf574 100644
--- a/core/modules/indexers/tag-indexer.js
+++ b/core/modules/indexers/tag-indexer.js
@@ -67,7 +67,57 @@ TagSubIndexer.prototype.rebuild = function() {
 };
 
 TagSubIndexer.prototype.update = function(updateDescriptor) {
-	this.index = null;
+	// If the index hasn't been built yet, no update needed
+	if(this.index === null) {
+		return;
+	}
+	// Determine whether the old/new tiddler is visible to this iterator
+	var oldVisible = this._isVisible(updateDescriptor.old),
+		newVisible = this._isVisible(updateDescriptor["new"]),
+		self = this;
+	// Remove old tags from index
+	if(oldVisible && updateDescriptor.old.tiddler) {
+		var oldTitle = updateDescriptor.old.tiddler.fields.title,
+			oldTags = updateDescriptor.old.tiddler.fields.tags || [];
+		$tw.utils.each(oldTags,function(tag) {
+			if(self.index[tag]) {
+				var idx = self.index[tag].titles.indexOf(oldTitle);
+				if(idx !== -1) {
+					self.index[tag].titles.splice(idx,1);
+					if(self.index[tag].titles.length === 0) {
+						delete self.index[tag];
+					}
+				}
+			}
+		});
+	}
+	// Add new tags to index
+	if(newVisible && updateDescriptor["new"].tiddler) {
+		var newTitle = updateDescriptor["new"].tiddler.fields.title,
+			newTags = updateDescriptor["new"].tiddler.fields.tags || [];
+		$tw.utils.each(newTags,function(tag) {
+			if(!self.index[tag]) {
+				self.index[tag] = {isSorted: false, titles: [newTitle]};
+			} else if(self.index[tag].titles.indexOf(newTitle) === -1) {
+				self.index[tag].titles.push(newTitle);
+				self.index[tag].isSorted = false;
+			}
+		});
+	}
+};
+
+/*
+Determine whether a tiddler described by a descriptor is visible to this sub-indexer's iterator
+*/
+TagSubIndexer.prototype._isVisible = function(descriptor) {
+	if(this.iteratorMethod === "each") {
+		return descriptor.exists;
+	} else if(this.iteratorMethod === "eachShadow") {
+		return descriptor.shadow;
+	} else {
+		// eachTiddlerPlusShadows and eachShadowPlusTiddlers both visit all tiddlers and shadows
+		return descriptor.exists || descriptor.shadow;
+	}
 };
 
 TagSubIndexer.prototype.lookup = function(tag) {
diff --git a/core/modules/utils/linked-list.js b/core/modules/utils/linked-list.js
index 5afab69d62f..ab0311234b0 100644
--- a/core/modules/utils/linked-list.js
+++ b/core/modules/utils/linked-list.js
@@ -59,14 +59,48 @@ LinkedList.prototype.push = function(/* values */) {
 LinkedList.prototype.pushTop = function(value) {
 	var t;
 	if($tw.utils.isArray(value)) {
-		for(t=0; t<value.length; t++) {
-			_assertString(value[t]);
-		}
-		for(t=0; t<value.length; t++) {
-			_removeOne(this,value[t]);
-		}
-		for(t=0; t<value.length; t++) {
-			_linkToEnd(this,value[t]);
+		if(this.length === 0) {
+			// Fast path for empty list: skip removal pass
+			for(t = 0; t < value.length; t++) {
+				_assertString(value[t]);
+			}
+			var prev = null,
+				useInline = true;
+			for(t = 0; t < value.length; t++) {
+				if(useInline) {
+					var v = value[t];
+					var old = this.next.get(v);
+					if(old !== undefined) {
+						// Duplicate found: switch to _linkToEnd for this and all remaining elements
+						useInline = false;
+						_linkToEnd(this,v);
+					} else {
+						// Inline the common case of _linkToEnd for new unique values
+						this.next.set(v,null);
+						this.prev.set(v,prev);
+						if(prev !== null) {
+							this.next.set(prev,v);
+						} else {
+							this.next.set(null,v);
+						}
+						this.prev.set(null,v);
+						this.length++;
+						prev = v;
+					}
+				} else {
+					_linkToEnd(this,value[t]);
+				}
+			}
+		} else {
+			for(t=0; t<value.length; t++) {
+				_assertString(value[t]);
+			}
+			for(t=0; t<value.length; t++) {
+				_removeOne(this,value[t]);
+			}
+			for(t=0; t<value.length; t++) {
+				_linkToEnd(this,value[t]);
+			}
 		}
 	} else {
 		_assertString(value);
diff --git a/core/modules/wiki.js b/core/modules/wiki.js
index aefe65110d3..bb99962bae3 100755
--- a/core/modules/wiki.js
+++ b/core/modules/wiki.js
@@ -1400,15 +1400,15 @@ exports.search = function(text,options) {
 		fields.push("text");
 	}
 	// Function to check a given tiddler for the search term
-	var searchTiddler = function(title) {
+	var searchTiddler = function(tiddler,title) {
 		if(!searchTermsRegExps) {
 			return true;
 		}
-		var notYetFound = searchTermsRegExps.slice();
-
-		var tiddler = self.getTiddler(title);
 		if(!tiddler) {
-			tiddler = new $tw.Tiddler({title: title, text: "", type: "text/vnd.tiddlywiki"});
+			tiddler = self.getTiddler(title);
+			if(!tiddler) {
+				tiddler = new $tw.Tiddler({title: title, text: "", type: "text/vnd.tiddlywiki"});
+			}
 		}
 		var contentTypeInfo = $tw.config.contentTypeInfo[tiddler.fields.type] || $tw.config.contentTypeInfo["text/vnd.tiddlywiki"],
 			searchFields;
@@ -1424,6 +1424,33 @@ exports.search = function(text,options) {
 		} else {
 			searchFields = fields;
 		}
+		// Fast path for single search term (avoids array slice/splice per tiddler)
+		if(searchTermsRegExps.length === 1) {
+			var singleRegExp = searchTermsRegExps[0];
+			for(var fieldIndex=0; fieldIndex<searchFields.length; fieldIndex++) {
+				var fieldName = searchFields[fieldIndex];
+				if(fieldName === "text" && contentTypeInfo.encoding !== "utf8") {
+					continue;
+				}
+				var str = tiddler.fields[fieldName];
+				if(str) {
+					if($tw.utils.isArray(str)) {
+						for(var s=0; s<str.length; s++) {
+							if(singleRegExp.test(str[s])) {
+								return true;
+							}
+						}
+					} else {
+						str = tiddler.getFieldString(fieldName);
+						if(singleRegExp.test(str)) {
+							return true;
+						}
+					}
+				}
+			}
+			return false;
+		}
+		var notYetFound = searchTermsRegExps.slice();
 		for(var fieldIndex=0; notYetFound.length>0 && fieldIndex<searchFields.length; fieldIndex++) {
 			// Don't search the text field if the content type is binary
 			var fieldName = searchFields[fieldIndex];
@@ -1463,7 +1490,7 @@ exports.search = function(text,options) {
 	var results = [],
 		source = options.source || this.each;
 	source(function(tiddler,title) {
-		if(searchTiddler(title) !== invert) {
+		if(searchTiddler(tiddler,title) !== invert) {
 			results.push(title);
 		}
 	});
diff --git a/editions/performance/tiddlywiki.info b/editions/performance/tiddlywiki.info
new file mode 100644
index 00000000000..9228445fee5
--- /dev/null
+++ b/editions/performance/tiddlywiki.info
@@ -0,0 +1,10 @@
+{
+	"description": "Performance measurement edition",
+	"plugins": [
+		"tiddlywiki/performance"
+	],
+	"themes": [
+		"tiddlywiki/vanilla",
+		"tiddlywiki/snowwhite"
+	]
+}
diff --git a/editions/prerelease/tiddlywiki.info b/editions/prerelease/tiddlywiki.info
index 2d779069f46..31ca019b5eb 100644
--- a/editions/prerelease/tiddlywiki.info
+++ b/editions/prerelease/tiddlywiki.info
@@ -14,6 +14,7 @@
 		"tiddlywiki/jszip",
 		"tiddlywiki/confetti",
 		"tiddlywiki/tour",
+		"tiddlywiki/performance",
 		"tiddlywiki/dom-to-image"
 	],
 	"themes": [
diff --git a/plugins/tiddlywiki/performance/perf-replay-command.js b/plugins/tiddlywiki/performance/perf-replay-command.js
new file mode 100644
index 00000000000..5a7a98b9b34
--- /dev/null
+++ b/plugins/tiddlywiki/performance/perf-replay-command.js
@@ -0,0 +1,230 @@
+/*\
+title: $:/plugins/tiddlywiki/performance/perf-replay-command.js
+type: application/javascript
+module-type: command
+
+Command to replay a recorded performance timeline against the current wiki
+
+Usage: --perf-replay <timeline.json> [--no-coalesce]
+
+Loads the wiki (use --load before this command), builds a widget tree
+using fakeDocument, then replays the recorded store modifications
+batch by batch, measuring refresh performance for each batch.
+
+\*/
+
+"use strict";
+
+exports.info = {
+	name: "perf-replay",
+	synchronous: false
+};
+
+var Command = function(params,commander,callback) {
+	this.params = params;
+	this.commander = commander;
+	this.callback = callback;
+};
+
+Command.prototype.execute = function() {
+	var self = this,
+		fs = require("fs"),
+		path = require("path"),
+		wiki = this.commander.wiki,
+		widget = require("$:/core/modules/widgets/widget.js");
+	// Parse parameters
+	if(this.params.length < 1) {
+		return "Missing timeline filename. Usage: --perf-replay <timeline.json>";
+	}
+	var timelinePath = this.params[0];
+	// Load timeline
+	var timelineData;
+	try {
+		timelineData = JSON.parse(fs.readFileSync(timelinePath,"utf8"));
+	} catch(e) {
+		return "Error reading timeline file: " + e.message;
+	}
+	if(!Array.isArray(timelineData) || timelineData.length === 0) {
+		return "Timeline file is empty or invalid";
+	}
+	// Count tiddlers in wiki
+	var tiddlerCount = 0;
+	wiki.each(function() { tiddlerCount++; });
+	// Build a widget tree against fakeDocument (mirroring what render.js does in the browser)
+	var PAGE_TEMPLATE_TITLE = "$:/core/ui/RootTemplate";
+	// Create root widget
+	var rootWidget = new widget.widget({
+		type: "widget",
+		children: []
+	},{
+		wiki: wiki,
+		document: $tw.fakeDocument
+	});
+	// Enable performance instrumentation
+	var perf = new $tw.Performance(true);
+	// Wrap filter execution with perf measurement
+	var origCompileFilter = wiki.compileFilter;
+	var filterInvocations = 0;
+	wiki.compileFilter = function(filterString) {
+		var compiledFilter = origCompileFilter.call(wiki,filterString);
+		return perf.measure("filter: " + filterString.substring(0,80),function(source,widget) {
+			filterInvocations++;
+			return compiledFilter.call(this,source,widget);
+		});
+	};
+	// Re-initialise parsers so filters get wrapped
+	wiki.clearCache(null);
+	// Build and render the page widget tree
+	var pageWidgetNode = wiki.makeTranscludeWidget(PAGE_TEMPLATE_TITLE,{
+		document: $tw.fakeDocument,
+		parentWidget: rootWidget,
+		recursionMarker: "no"
+	});
+	var pageContainer = $tw.fakeDocument.createElement("div");
+	var renderStart = $tw.utils.timer();
+	pageWidgetNode.render(pageContainer,null);
+	var renderTime = $tw.utils.timer(renderStart);
+	// Link root widget
+	rootWidget.domNodes = [pageContainer];
+	rootWidget.children = [pageWidgetNode];
+	// Group timeline events by batch
+	var batches = [];
+	var currentBatch = null;
+	$tw.utils.each(timelineData,function(event) {
+		if(!currentBatch || event.batch !== currentBatch.batchId) {
+			currentBatch = {batchId: event.batch, events: []};
+			batches.push(currentBatch);
+		}
+		currentBatch.events.push(event);
+	});
+	// Replay each batch and measure refresh
+	var results = [],
+		totalRefreshTime = 0,
+		totalFilterInvocations = 0;
+	self.commander.streams.output.write("\nPerformance Timeline Replay\n");
+	self.commander.streams.output.write("==========================\n");
+	self.commander.streams.output.write("Wiki: " + tiddlerCount + " tiddlers\n");
+	self.commander.streams.output.write("Timeline: " + timelineData.length + " operations in " + batches.length + " batches\n");
+	self.commander.streams.output.write("Initial render: " + renderTime.toFixed(2) + "ms\n\n");
+	self.commander.streams.output.write(padRight("Batch",8) + padRight("Ops",6) + padRight("Changed",10) +
+		padRight("Refresh(ms)",14) + padRight("Filters",10) + "Tiddlers Changed\n");
+	self.commander.streams.output.write(padRight("-----",8) + padRight("---",6) + padRight("-------",10) +
+		padRight("-----------",14) + padRight("-------",10) + "----------------\n");
+	$tw.utils.each(batches,function(batch,index) {
+		// Apply all operations in this batch directly (bypassing the intercepted addTiddler
+		// to avoid re-recording)
+		var changedTiddlers = Object.create(null);
+		$tw.utils.each(batch.events,function(event) {
+			if(event.op === "add") {
+				wiki.addTiddler(new $tw.Tiddler(event.fields));
+				changedTiddlers[event.title] = {modified: true};
+			} else if(event.op === "delete") {
+				wiki.deleteTiddler(event.title);
+				changedTiddlers[event.title] = {deleted: true};
+			}
+		});
+		// Measure refresh
+		filterInvocations = 0;
+		var refreshStart = $tw.utils.timer();
+		pageWidgetNode.refresh(changedTiddlers);
+		var refreshTime = $tw.utils.timer(refreshStart);
+		totalRefreshTime += refreshTime;
+		totalFilterInvocations += filterInvocations;
+		var changedTitles = Object.keys(changedTiddlers);
+		var titlesDisplay = changedTitles.slice(0,3).join(", ");
+		if(changedTitles.length > 3) {
+			titlesDisplay += " (+" + (changedTitles.length - 3) + " more)";
+		}
+		results.push({
+			batch: index + 1,
+			ops: batch.events.length,
+			changed: changedTitles.length,
+			refreshMs: refreshTime,
+			filters: filterInvocations,
+			tiddlers: changedTitles
+		});
+		self.commander.streams.output.write(
+			padRight(String(index + 1),8) +
+			padRight(String(batch.events.length),6) +
+			padRight(String(changedTitles.length),10) +
+			padRight(refreshTime.toFixed(2),14) +
+			padRight(String(filterInvocations),10) +
+			titlesDisplay + "\n"
+		);
+	});
+	// Summary statistics
+	var refreshTimes = results.map(function(r) { return r.refreshMs; }).sort(function(a,b) { return a - b; });
+	var p50 = percentile(refreshTimes,50);
+	var p95 = percentile(refreshTimes,95);
+	var p99 = percentile(refreshTimes,99);
+	var maxRefresh = refreshTimes[refreshTimes.length - 1] || 0;
+	var meanRefresh = batches.length > 0 ? totalRefreshTime / batches.length : 0;
+	self.commander.streams.output.write("\nSummary\n");
+	self.commander.streams.output.write("-------\n");
+	self.commander.streams.output.write("Initial render:      " + renderTime.toFixed(2) + "ms\n");
+	self.commander.streams.output.write("Total refresh time:  " + totalRefreshTime.toFixed(2) + "ms\n");
+	self.commander.streams.output.write("Mean refresh:        " + meanRefresh.toFixed(2) + "ms\n");
+	self.commander.streams.output.write("P50 refresh:         " + p50.toFixed(2) + "ms\n");
+	self.commander.streams.output.write("P95 refresh:         " + p95.toFixed(2) + "ms\n");
+	self.commander.streams.output.write("P99 refresh:         " + p99.toFixed(2) + "ms\n");
+	self.commander.streams.output.write("Max refresh:         " + maxRefresh.toFixed(2) + "ms\n");
+	self.commander.streams.output.write("Total filters run:   " + totalFilterInvocations + "\n");
+	// Output filter breakdown
+	self.commander.streams.output.write("\nTop Filter Execution Times\n");
+	self.commander.streams.output.write("--------------------------\n");
+	var measures = perf.measures;
+	var orderedMeasures = Object.keys(measures).sort(function(a,b) {
+		return measures[b].time - measures[a].time;
+	}).slice(0,20);
+	$tw.utils.each(orderedMeasures,function(name) {
+		var m = measures[name];
+		self.commander.streams.output.write(
+			padRight(m.time.toFixed(2) + "ms",14) +
+			padRight(String(m.invocations) + "x",10) +
+			padRight((m.time / m.invocations).toFixed(3) + "ms avg",16) +
+			name + "\n"
+		);
+	});
+	// Write JSON results
+	var jsonResultPath = timelinePath.replace(/\.json$/,"") + "-results.json";
+	try {
+		fs.writeFileSync(jsonResultPath,JSON.stringify({
+			wiki: {tiddlerCount: tiddlerCount},
+			timeline: {operations: timelineData.length, batches: batches.length},
+			initialRender: renderTime,
+			summary: {
+				totalRefreshTime: totalRefreshTime,
+				meanRefresh: meanRefresh,
+				p50: p50,
+				p95: p95,
+				p99: p99,
+				maxRefresh: maxRefresh,
+				totalFilterInvocations: totalFilterInvocations
+			},
+			batches: results,
+			topFilters: orderedMeasures.map(function(name) {
+				return {name: name, time: measures[name].time, invocations: measures[name].invocations};
+			})
+		},null,"\t"),"utf8");
+		self.commander.streams.output.write("\nDetailed results written to: " + jsonResultPath + "\n");
+	} catch(e) {
+		self.commander.streams.output.write("\nWarning: Could not write results file: " + e.message + "\n");
+	}
+	self.callback(null);
+	return null;
+};
+
+function percentile(sortedArray,p) {
+	if(sortedArray.length === 0) return 0;
+	var index = Math.ceil(sortedArray.length * p / 100) - 1;
+	return sortedArray[Math.max(0,index)];
+}
+
+function padRight(str,width) {
+	while(str.length < width) {
+		str += " ";
+	}
+	return str;
+}
+
+exports.Command = Command;
diff --git a/plugins/tiddlywiki/performance/plugin.info b/plugins/tiddlywiki/performance/plugin.info
new file mode 100644
index 00000000000..720f16bcbda
--- /dev/null
+++ b/plugins/tiddlywiki/performance/plugin.info
@@ -0,0 +1,7 @@
+{
+	"title": "$:/plugins/tiddlywiki/performance",
+	"name": "Performance",
+	"description": "Record and replay wiki store modifications for performance testing",
+	"list": "readme ui",
+	"stability": "STABILITY_1_EXPERIMENTAL"
+}
diff --git a/plugins/tiddlywiki/performance/readme.tid b/plugins/tiddlywiki/performance/readme.tid
new file mode 100644
index 00000000000..bf949dd4601
--- /dev/null
+++ b/plugins/tiddlywiki/performance/readme.tid
@@ -0,0 +1,202 @@
+title: $:/plugins/tiddlywiki/performance/readme
+
+! Performance Testing Plugin
+
+This plugin provides a framework for measuring the performance of TiddlyWiki's refresh cycle — the process that updates the display when tiddlers are modified.
+
+The idea is to capture a realistic workload by recording store modifications while a user interacts with a wiki in the browser, and then replaying those modifications under Node.js where the refresh cycle can be precisely measured in isolation.
+
+!! Motivation
+
+An important motivation for this framework is to enable LLMs to iteratively optimise TiddlyWiki's performance. The workflow is:
+
+# An LLM makes a change to the TiddlyWiki codebase (e.g. optimising a filter operator, caching a computation, or restructuring a widget's refresh logic)
+# The LLM runs `--perf-replay` against a recorded timeline to measure the impact
+# The LLM reads the JSON results file to determine whether the change improved, regressed, or had no effect on performance
+# The LLM iterates: tries another approach, measures again, and converges on the best solution
+
+This tight edit-measure-iterate loop works because `--perf-replay` runs entirely under Node.js with no browser required, produces machine-readable JSON output, and completes in seconds.
+
+!! How It Works
+
+The framework has two parts:
+
+!!! 1. Recording (Browser)
+
+The plugin intercepts `wiki.addTiddler()` and `wiki.deleteTiddler()` to capture every store modification as it happens. Each operation is recorded with:
+
+* A sequence number and high-resolution timestamp
+* The full tiddler fields (so the exact state can be recreated)
+* A batch identifier that tracks TiddlyWiki's change batching via `$tw.utils.nextTick()`
+
+The batch tracking is important because TiddlyWiki groups multiple store changes that occur in the same tick into a single refresh cycle. The recorder preserves these batch boundaries so that playback triggers the same pattern of refreshes.
+
+!!! 2. Playback (Node.js)
+
+The `--perf-replay` command loads a wiki and builds the full widget tree using TiddlyWiki's `$tw.fakeDocument` — the lightweight DOM implementation used for server-side rendering. It then replays the recorded timeline batch by batch, calling `widgetNode.refresh(changedTiddlers)` after each batch and measuring how long it takes.
+
+This means we are measuring TiddlyWiki's own refresh logic (widget tree traversal, filter evaluation, DOM diffing) in isolation from browser layout and paint. This is intentional — it lets us identify performance bottlenecks within TiddlyWiki itself, independent of which browser is being used.
+
+!! Why Store-Level Recording?
+
+An alternative would be to record DOM events (clicks, keystrokes) and replay them in a headless browser. Store-level recording was chosen instead because:
+
+* The refresh cycle responds to ''store changes'', not DOM events — store modifications are the natural input
+* Store changes are fully deterministic and reproducible
+* No DOM dependency means playback works in pure Node.js with no headless browser to install
+* A headless browser would add its own overhead, making measurements less precise
+
+!! Recording
+
+# Include this plugin in your wiki
+# Open the Control Panel and find the "Performance Testing Recorder" tab
+# Click "Start Recording"
+# Interact with the wiki — open tiddlers, edit, type, navigate, switch tabs
+# Click "Stop Recording"
+# Download the `timeline.json` file
+
+!!! Draft Coalescing
+
+When editing a tiddler, TiddlyWiki writes to draft tiddlers on every keystroke. By default, the recorder coalesces rapid draft updates within the same batch, keeping only the last update. This produces a more compact timeline that focuses on the refresh-relevant changes.
+
+Uncheck "Coalesce rapid draft updates" to record every individual keystroke. This is useful when you specifically want to measure the performance impact of rapid typing.
+
+!! Playback
+
+```
+tiddlywiki editions/performance --load mywiki.html --perf-replay timeline.json
+```
+
+Or from any edition that includes this plugin:
+
+```
+tiddlywiki myedition --perf-replay timeline.json
+```
+
+Playback runs at full speed with no delays between batches. The recorded timestamps are preserved in the timeline for reference but are not used for pacing.
+
+!! What Gets Measured
+
+* ''Initial render time'' — the time to build and render the full widget tree from scratch
+* ''Refresh time per batch'' — the time `widgetNode.refresh(changedTiddlers)` takes for each batch of store modifications
+* ''Filter execution'' — individual filter timings and invocation counts, showing which filters are the most expensive
+* ''Statistical summary'' — mean, P50, P95, P99, and maximum refresh times across all batches
+
+!! Output
+
+The command produces two forms of output:
+
+!!! Text Report (stdout)
+
+A human-readable table printed to the console showing per-batch timings, a summary with percentile statistics, and a breakdown of the most expensive filter executions.
+
+!!! JSON Results File
+
+A `<timeline-name>-results.json` file is written alongside the input timeline. This is the primary output for automated consumption. The file contains:
+
+```json
+{
+  "wiki": {
+    "tiddlerCount": 2076
+  },
+  "timeline": {
+    "operations": 156,
+    "batches": 42
+  },
+  "initialRender": 55.46,
+  "summary": {
+    "totalRefreshTime": 234.5,
+    "meanRefresh": 5.58,
+    "p50": 4.12,
+    "p95": 18.7,
+    "p99": 31.2,
+    "maxRefresh": 31.2,
+    "totalFilterInvocations": 4821
+  },
+  "batches": [
+    {
+      "batch": 1,
+      "ops": 1,
+      "changed": 1,
+      "refreshMs": 12.3,
+      "filters": 293,
+      "tiddlers": ["$:/StoryList"]
+    }
+  ],
+  "topFilters": [
+    {
+      "name": "filter: [subfilter{$:/core/config/GlobalImportFilter}]",
+      "time": 5.65,
+      "invocations": 5
+    }
+  ]
+}
+```
+
+All times are in milliseconds. The key fields for automated analysis:
+
+* `summary.totalRefreshTime` — the single most important number: total time spent in refresh across all batches
+* `summary.meanRefresh` — average refresh time per batch
+* `summary.p95` / `summary.p99` — tail latency indicators
+* `initialRender` — time to build the widget tree from scratch (measures startup cost)
+* `batches[].refreshMs` — per-batch breakdown, useful for identifying which user actions are expensive
+* `topFilters[]` — the most expensive filters by total execution time, useful for identifying optimisation targets
+
+!! Example: LLM Optimisation Workflow
+
+An LLM optimising TiddlyWiki performance would follow this pattern:
+
+!!! Step 1: Establish baseline
+
+```
+node ./tiddlywiki.js editions/performance --load mywiki.html --perf-replay timeline.json
+```
+
+Read `timeline-results.json` and note the baseline `summary.totalRefreshTime`.
+
+!!! Step 2: Make a change
+
+Edit a source file (e.g. optimise a filter operator in `core/modules/filters/`).
+
+!!! Step 3: Measure impact
+
+Run the same `--perf-replay` command again and read the new `timeline-results.json`.
+
+!!! Step 4: Compare
+
+Compare `summary.totalRefreshTime` and `summary.p95` between baseline and new results. If improved, keep the change. If regressed, revert and try a different approach.
+
+!!! Step 5: Iterate
+
+Repeat steps 2-4 until the target metric is optimised.
+
+The JSON results file makes step 4 straightforward — an LLM can read two JSON files and compare numeric fields directly without parsing tabular text output.
+
+!! Timeline Format
+
+The timeline is a JSON array of operations:
+
+```json
+[
+  {
+    "seq": 0,
+    "t": 123.45,
+    "batch": 0,
+    "op": "add",
+    "title": "$:/StoryList",
+    "isDraft": false,
+    "fields": {
+      "title": "$:/StoryList",
+      "list": "GettingStarted",
+      "text": ""
+    }
+  }
+]
+```
+
+* `seq` — sequential operation number
+* `t` — milliseconds since recording started
+* `batch` — batch identifier (operations in the same batch trigger a single refresh)
+* `op` — `"add"` or `"delete"`
+* `isDraft` — whether this is a draft tiddler (used for coalescing)
+* `fields` — complete tiddler fields (null for delete operations)
diff --git a/plugins/tiddlywiki/performance/recorder.js b/plugins/tiddlywiki/performance/recorder.js
new file mode 100644
index 00000000000..f38a849f0fa
--- /dev/null
+++ b/plugins/tiddlywiki/performance/recorder.js
@@ -0,0 +1,143 @@
+/*\
+title: $:/plugins/tiddlywiki/performance/recorder.js
+type: application/javascript
+module-type: startup
+
+Store modification recorder for performance testing.
+Intercepts wiki.addTiddler() and wiki.deleteTiddler() to capture
+a timeline of all store modifications with batch boundary tracking.
+
+\*/
+
+"use strict";
+
+exports.name = "perf-recorder";
+exports.platforms = ["browser"];
+exports.after = ["load-modules"];
+exports.synchronous = true;
+
+exports.startup = function() {
+	var STATE_TIDDLER = "$:/state/performance/recording",
+		TIMELINE_TIDDLER = "$:/temp/performance/timeline",
+		COALESCE_CONFIG = "$:/config/performance/coalesce-drafts",
+		timeline = [],
+		seq = 0,
+		startTime = null,
+		recording = false,
+		batchId = 0,
+		currentBatch = 0,
+		origNextTick = $tw.utils.nextTick,
+		origAddTiddler = $tw.wiki.addTiddler.bind($tw.wiki),
+		origDeleteTiddler = $tw.wiki.deleteTiddler.bind($tw.wiki);
+
+	// Patch nextTick to track batch boundaries
+	$tw.utils.nextTick = function(fn) {
+		origNextTick(function() {
+			if(recording) {
+				currentBatch = ++batchId;
+			}
+			fn();
+		});
+	};
+
+	// Patch addTiddler
+	$tw.wiki.addTiddler = function(tiddler) {
+		if(recording) {
+			if(!(tiddler instanceof $tw.Tiddler)) {
+				tiddler = new $tw.Tiddler(tiddler);
+			}
+			var title = tiddler.fields.title;
+			// Skip our own state/timeline tiddlers
+			if(title !== STATE_TIDDLER && title !== TIMELINE_TIDDLER) {
+				timeline.push({
+					seq: seq++,
+					t: $tw.utils.timer(startTime),
+					batch: currentBatch,
+					op: "add",
+					title: title,
+					isDraft: tiddler.hasField("draft.of"),
+					fields: tiddler.getFieldStrings()
+				});
+			}
+		}
+		return origAddTiddler.apply(null,arguments);
+	};
+
+	// Patch deleteTiddler
+	$tw.wiki.deleteTiddler = function(title) {
+		if(recording) {
+			if(title !== STATE_TIDDLER && title !== TIMELINE_TIDDLER) {
+				timeline.push({
+					seq: seq++,
+					t: $tw.utils.timer(startTime),
+					batch: currentBatch,
+					op: "delete",
+					title: title,
+					isDraft: false,
+					fields: null
+				});
+			}
+		}
+		return origDeleteTiddler.apply(null,arguments);
+	};
+
+	// Listen for recording state changes
+	$tw.wiki.addEventListener("change",function(changes) {
+		if(STATE_TIDDLER in changes) {
+			var state = $tw.wiki.getTiddlerText(STATE_TIDDLER,"").trim();
+			if(state === "yes" && !recording) {
+				// Start recording
+				timeline = [];
+				seq = 0;
+				batchId = 0;
+				currentBatch = 0;
+				startTime = $tw.utils.timer();
+				recording = true;
+				console.log("performance: Recording started");
+			} else if(state !== "yes" && recording) {
+				// Stop recording and save timeline
+				recording = false;
+				var coalesce = $tw.wiki.getTiddlerText(COALESCE_CONFIG,"yes").trim() === "yes";
+				var output = coalesce ? coalesceDrafts(timeline) : timeline;
+				origAddTiddler(new $tw.Tiddler({
+					title: TIMELINE_TIDDLER,
+					type: "application/json",
+					text: JSON.stringify(output,null,"\t")
+				}));
+				console.log("performance: Recording stopped. " + timeline.length + " operations captured" +
+					(coalesce ? " (" + output.length + " after coalescing drafts)" : ""));
+			}
+		}
+	});
+
+	/*
+	Coalesce rapid draft tiddler updates within the same batch.
+	Keeps only the last update for each draft tiddler per batch.
+	*/
+	function coalesceDrafts(events) {
+		var result = [],
+			i = 0;
+		while(i < events.length) {
+			var event = events[i];
+			if(event.isDraft && event.op === "add") {
+				// Look ahead for later updates to this same draft in the same batch
+				var lastIndex = i;
+				for(var j = i + 1; j < events.length; j++) {
+					if(events[j].batch !== event.batch) {
+						break;
+					}
+					if(events[j].title === event.title && events[j].op === "add") {
+						lastIndex = j;
+					}
+				}
+				// Keep only the last one, but fix its seq to maintain ordering
+				result.push(events[lastIndex]);
+				i = lastIndex + 1;
+			} else {
+				result.push(event);
+				i++;
+			}
+		}
+		return result;
+	}
+};
diff --git a/plugins/tiddlywiki/performance/ui.tid b/plugins/tiddlywiki/performance/ui.tid
new file mode 100644
index 00000000000..cfba60c7bd0
--- /dev/null
+++ b/plugins/tiddlywiki/performance/ui.tid
@@ -0,0 +1,48 @@
+title: $:/plugins/tiddlywiki/performance/ui
+caption: Recorder
+
+! Performance Testing Recorder
+
+<$let
+	state="$:/state/performance/recording"
+	timeline="$:/temp/performance/timeline"
+	coalesceConfig="$:/config/performance/coalesce-drafts"
+>
+
+!! Recording
+
+<$reveal state=<<state>> type="nomatch" text="yes">
+<$button set=<<state>> setTo="yes" class="tc-btn-big-green">Start Recording</$button>
+</$reveal>
+
+<$reveal state=<<state>> type="match" text="yes">
+<$button set=<<state>> setTo="no" class="tc-btn-big-green" style="background: #d33;">Stop Recording</$button>
+&nbsp; //Recording in progress...//
+</$reveal>
+
+!! Options
+
+<$checkbox tiddler=<<coalesceConfig>> field="text" checked="yes" unchecked="no" default="yes"> Coalesce rapid draft updates</$checkbox>
+
+!! Timeline
+
+<$reveal type="nomatch" state=<<timeline>> text="">
+
+<$let timelineText={{$(timeline)$}}>
+<$vars count={{{ [<timeline>get[text]jsonextract[]] +[count[]] }}}>
+Timeline contains <<count>> operations.
+</$vars>
+
+<$button>
+<$action-sendmessage $message="tm-download-file" $param=<<timeline>> filename="timeline.json"/>
+Download timeline.json
+</$button>
+
+</$let>
+</$reveal>
+
+<$reveal type="match" state=<<timeline>> text="">
+No timeline recorded yet. Click "Start Recording", interact with the wiki, then click "Stop Recording".
+</$reveal>
+
+</$let>