From a10fcfd58e3a497bbddf3b17fcffe43ac0f1ea4e Mon Sep 17 00:00:00 2001
From: Dan Stillman <dstillman@zotero.org>
Date: Tue, 1 Mar 2022 02:43:58 -0500
Subject: [PATCH] Speed up comparison of items with huge numbers of tags

Can cause a freeze while syncing items with 1000s of tags
---
 chrome/content/zotero/xpcom/data/dataObjectUtilities.js | 9 +++++++--
 chrome/content/zotero/xpcom/data/tags.js                | 8 +++++---
 2 files changed, 12 insertions(+), 5 deletions(-)

diff --git a/chrome/content/zotero/xpcom/data/dataObjectUtilities.js b/chrome/content/zotero/xpcom/data/dataObjectUtilities.js
index 1f3ca4717d..7e0ca16e37 100644
--- a/chrome/content/zotero/xpcom/data/dataObjectUtilities.js
+++ b/chrome/content/zotero/xpcom/data/dataObjectUtilities.js
@@ -505,11 +505,16 @@ Zotero.DataObjectUtilities = {
 	},
 	
 	_tagsDiff: function (data1, data2 = []) {
+		var equals = Zotero.Tags.equals.bind(Zotero.Tags);
+		
+		var cleanedData1 = data1.map(x => Zotero.Tags.cleanData(x));
+		var cleanedData2 = data2.map(x => Zotero.Tags.cleanData(x));
+		
 		var changeset = [];
 		outer:
 		for (let i = 0; i < data1.length; i++) {
 			for (let j = 0; j < data2.length; j++) {
-				if (Zotero.Tags.equals(data1[i], data2[j])) {
+				if (equals(cleanedData1[i], cleanedData2[j], { skipClean: true })) {
 					continue outer;
 				}
 			}
@@ -522,7 +527,7 @@ Zotero.DataObjectUtilities = {
 		outer:
 		for (let i = 0; i < data2.length; i++) {
 			for (let j = 0; j < data1.length; j++) {
-				if (Zotero.Tags.equals(data2[i], data1[j])) {
+				if (equals(cleanedData2[i], cleanedData1[j], { skipClean: true })) {
 					continue outer;
 				}
 			}
diff --git a/chrome/content/zotero/xpcom/data/tags.js b/chrome/content/zotero/xpcom/data/tags.js
index 1324c44407..385341e7ce 100644
--- a/chrome/content/zotero/xpcom/data/tags.js
+++ b/chrome/content/zotero/xpcom/data/tags.js
@@ -944,9 +944,11 @@ Zotero.Tags = new function() {
 	/**
 	 * Compare two API JSON tag objects
 	 */
-	this.equals = function (data1, data2) {
-		data1 = this.cleanData(data1);
-		data2 = this.cleanData(data2);
+	this.equals = function (data1, data2, options = {}) {
+		if (!options.skipClean) {
+			data1 = this.cleanData(data1);
+			data2 = this.cleanData(data2);
+		}
 		return data1.tag === data2.tag
 			&& ((!data1.type && !data2.type) || data1.type === data2.type);
 	},