diff --git a/src/categories/topics.js b/src/categories/topics.js
index 918cc4c244..64e9046614 100644
--- a/src/categories/topics.js
+++ b/src/categories/topics.js
@@ -99,7 +99,8 @@ module.exports = function (Categories) {
 			most_views: `cid:${cid}:tids:views`,
 		};
 
-		const set = new Set([sortToSet.hasOwnProperty(sort) ? sortToSet[sort] : `cid:${cid}:tids`]);
+		const mainSet = sortToSet.hasOwnProperty(sort) ? sortToSet[sort] : `cid:${cid}:tids`;
+		const set = new Set([mainSet]);
 
 		if (data.tag) {
 			if (Array.isArray(data.tag)) {
@@ -116,6 +117,7 @@ module.exports = function (Categories) {
 		}
 
 		if (parseInt(cid, 10) === -1 && uid > 0) {
+			set.delete(mainSet);
 			set.add(`uid:${uid}:inbox`);
 		}
 		const setValue = Array.from(set);
@@ -251,4 +253,24 @@ module.exports = function (Categories) {
 		});
 		notifications.push(notification, followers);
 	};
+
+	Categories.sortTidsBySet = async (tids, cid, sort) => {
+		sort = sort || meta.config.categoryTopicSort || 'recently_replied';
+		const sortToSet = {
+			recently_replied: `cid:${cid}:tids`,
+			recently_created: `cid:${cid}:tids:create`,
+			most_posts: `cid:${cid}:tids:posts`,
+			most_votes: `cid:${cid}:tids:votes`,
+			most_views: `cid:${cid}:tids:views`,
+		};
+
+		const orderBy = sortToSet[sort];
+		const scores = await db.sortedSetScores(orderBy, tids);
+		const sorted = tids
+			.map((tid, idx) => [tid, scores[idx]])
+			.sort(([, a], [, b]) => b - a)
+			.map(([tid]) => tid);
+
+		return sorted;
+	};
 };
diff --git a/src/controllers/activitypub/topics.js b/src/controllers/activitypub/topics.js
index 7a871a6876..68bcbc66a5 100644
--- a/src/controllers/activitypub/topics.js
+++ b/src/controllers/activitypub/topics.js
@@ -20,22 +20,6 @@ const validSorts = [
 	'recently_replied', 'recently_created', 'most_posts', 'most_votes', 'most_views',
 ];
 
-async function getTids(data) {
-	// Poor man's intersect used instead of getSortedSetIntersect because the zsets are huge
-	const sets = await categories.buildTopicsSortedSet(data);
-	const intersect = Array.isArray(sets);
-	const mainSet = intersect ? sets.shift() : sets;
-	let tids = await db.getSortedSetRevRange(mainSet, 0, 499);
-	if (!intersect) {
-		return tids.slice(data.start, data.stop + 1);
-	}
-
-	let intersection = await Promise.all(sets.map(async set => db.isSortedSetMembers(set, tids)));
-	intersection = intersection.reduce((memo, cur) => memo.map((show, idx) => show && cur[idx]));
-	tids = tids.filter((_, idx) => intersection[idx]);
-	return tids.slice(data.start, data.stop + 1);
-}
-
 controller.list = async function (req, res) {
 	if (!req.uid) {
 		return helpers.redirect(res, '/recent?cid=-1', false);
@@ -69,7 +53,8 @@ controller.list = async function (req, res) {
 	data.name = '[[world:name]]';
 	delete data.children;
 
-	const tids = await getTids(cidQuery);
+	let tids = await categories.getTopicIds(cidQuery);
+	tids = await categories.sortTidsBySet(tids, -1, sort); // sorting not handled if cid is -1
 	data.topicCount = tids.length;
 	data.topics = await topics.getTopicsByTids(tids, { uid: req.uid });
 	topics.calculateTopicIndices(data.topics, start);