From e4b10d42f9480c0505862a93f0b97d1c4270ed65 Mon Sep 17 00:00:00 2001
From: Jermolene <jeremy@jermolene.com>
Date: Thu, 21 Dec 2017 16:13:47 +0000
Subject: [PATCH] Optimise the tag filter

Spending a bit more time with Chrome dev tools, and further to 254e1ca, this optimisation reduces the rendering time for the sample TOC from 1.9s to about 0.9s...
---
 core/modules/filters/tag.js | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/core/modules/filters/tag.js b/core/modules/filters/tag.js
index a421c61d7..a0093f565 100644
--- a/core/modules/filters/tag.js
+++ b/core/modules/filters/tag.js
@@ -25,17 +25,18 @@ exports.tag = function(source,operator,options) {
 		});
 	} else {
 		// Old semantics:
+		var tiddlers = options.wiki.getTiddlersWithTag(operator.operand);
 		if(operator.prefix === "!") {
 			// Returns a copy of the input if operator.operand is missing
 			source(function(tiddler,title) {
-				if(tiddler && !tiddler.hasTag(operator.operand)) {
+				if(tiddlers.indexOf(title) === -1) {
 					results.push(title);
 				}
 			});
 		} else {
 			// Returns empty results if operator.operand is missing
 			source(function(tiddler,title) {
-				if(tiddler && tiddler.hasTag(operator.operand)) {
+				if(tiddlers.indexOf(title) !== -1) {
 					results.push(title);
 				}
 			});