diff --git a/install/package.json b/install/package.json
index 55e47bb9e4..15e29df711 100644
--- a/install/package.json
+++ b/install/package.json
@@ -107,10 +107,10 @@
         "nodebb-plugin-spam-be-gone": "2.3.1",
         "nodebb-plugin-web-push": "0.7.3",
         "nodebb-rewards-essentials": "1.0.1",
-        "nodebb-theme-harmony": "2.1.6",
+        "nodebb-theme-harmony": "2.1.7",
         "nodebb-theme-lavender": "7.1.18",
-        "nodebb-theme-peace": "2.2.39",
-        "nodebb-theme-persona": "14.1.5",
+        "nodebb-theme-peace": "2.2.40",
+        "nodebb-theme-persona": "14.1.6",
         "nodebb-widget-essentials": "7.0.36",
         "nodemailer": "6.10.0",
         "nprogress": "0.2.0",
diff --git a/public/language/en-GB/global.json b/public/language/en-GB/global.json
index 4ca7816332..7e66953d0a 100644
--- a/public/language/en-GB/global.json
+++ b/public/language/en-GB/global.json
@@ -95,6 +95,7 @@
 	"downvoted": "Downvoted",
 	"views": "Views",
 	"posters": "Posters",
+	"watching": "Watching",
 	"reputation": "Reputation",
 	"lastpost": "Last post",
 	"firstpost": "First post",
diff --git a/public/openapi/components/schemas/TopicObject.yaml b/public/openapi/components/schemas/TopicObject.yaml
index 3789aa9518..b26623072e 100644
--- a/public/openapi/components/schemas/TopicObject.yaml
+++ b/public/openapi/components/schemas/TopicObject.yaml
@@ -218,6 +218,8 @@ TopicObjectSlim:
           type: number
         postercount:
           type: number
+        followercount:
+          type: number
         scheduled:
           type: number
         deleted:
diff --git a/src/topics/data.js b/src/topics/data.js
index d411cbf329..76c027121d 100644
--- a/src/topics/data.js
+++ b/src/topics/data.js
@@ -10,9 +10,10 @@ const plugins = require('../plugins');
 
 const intFields = [
 	'tid', 'cid', 'uid', 'mainPid', 'postcount',
-	'viewcount', 'postercount', 'deleted', 'locked', 'pinned',
-	'pinExpiry', 'timestamp', 'upvotes', 'downvotes', 'lastposttime',
-	'deleterUid',
+	'viewcount', 'postercount', 'followercount',
+	'deleted', 'locked', 'pinned', 'pinExpiry',
+	'timestamp', 'upvotes', 'downvotes',
+	'lastposttime', 'deleterUid',
 ];
 
 module.exports = function (Topics) {
diff --git a/src/topics/follow.js b/src/topics/follow.js
index a89dfa57c5..d1afb7025c 100644
--- a/src/topics/follow.js
+++ b/src/topics/follow.js
@@ -48,29 +48,30 @@ module.exports = function (Topics) {
 	}
 
 	async function follow(tid, uid) {
-		await addToSets(`tid:${tid}:followers`, `uid:${uid}:followed_tids`, tid, uid);
+		await db.setAdd(`tid:${tid}:followers`, uid);
+		await db.sortedSetAdd(`uid:${uid}:followed_tids`, Date.now(), tid);
+		await updateFollowerCount(tid);
 	}
 
 	async function unfollow(tid, uid) {
-		await removeFromSets(`tid:${tid}:followers`, `uid:${uid}:followed_tids`, tid, uid);
+		await db.setRemove(`tid:${tid}:followers`, uid);
+		await db.sortedSetRemove(`uid:${uid}:followed_tids`, tid);
+		await updateFollowerCount(tid);
 	}
 
 	async function ignore(tid, uid) {
-		await addToSets(`tid:${tid}:ignorers`, `uid:${uid}:ignored_tids`, tid, uid);
+		await db.setAdd(`tid:${tid}:ignorers`, uid);
+		await db.sortedSetAdd(`uid:${uid}:ignored_tids`, Date.now(), tid);
 	}
 
 	async function unignore(tid, uid) {
-		await removeFromSets(`tid:${tid}:ignorers`, `uid:${uid}:ignored_tids`, tid, uid);
+		await db.setRemove(`tid:${tid}:ignorers`, uid);
+		await db.sortedSetRemove(`uid:${uid}:ignored_tids`, tid);
 	}
 
-	async function addToSets(set1, set2, tid, uid) {
-		await db.setAdd(set1, uid);
-		await db.sortedSetAdd(set2, Date.now(), tid);
-	}
-
-	async function removeFromSets(set1, set2, tid, uid) {
-		await db.setRemove(set1, uid);
-		await db.sortedSetRemove(set2, tid);
+	async function updateFollowerCount(tid) {
+		const count = await db.setCount(`tid:${tid}:followers`);
+		await Topics.setTopicField(tid, 'followercount', count);
 	}
 
 	Topics.isFollowing = async function (tids, uid) {
diff --git a/src/upgrades/4.3.0/normalize_thumbs_uploads.js b/src/upgrades/4.3.0/normalize_thumbs_uploads.js
index d5fc15820a..ef12d54f81 100644
--- a/src/upgrades/4.3.0/normalize_thumbs_uploads.js
+++ b/src/upgrades/4.3.0/normalize_thumbs_uploads.js
@@ -7,7 +7,7 @@ const crypto = require('crypto');
 
 module.exports = {
 	name: 'Normalize topic thumbnails, post & user uploads to same format',
-	timestamp: Date.UTC(2021, 1, 7),
+	timestamp: Date.UTC(2025, 3, 4),
 	method: async function () {
 		const { progress } = this;
 
diff --git a/src/upgrades/4.3.0/topic_follower_counts.js b/src/upgrades/4.3.0/topic_follower_counts.js
new file mode 100644
index 0000000000..81beff21fe
--- /dev/null
+++ b/src/upgrades/4.3.0/topic_follower_counts.js
@@ -0,0 +1,35 @@
+'use strict';
+
+const db = require('../../database');
+const batch = require('../../batch');
+
+
+module.exports = {
+	name: 'Set "followercount" on each topic object',
+	timestamp: Date.UTC(2025, 3, 15),
+	method: async function () {
+		const { progress } = this;
+
+		progress.total = await db.sortedSetCard('topics:tid');
+
+		await batch.processSortedSet('topics:tid', async (tids) => {
+			const keys = tids.map(tid => `tid:${tid}:followers`);
+			const followerCounts = await db.setsCount(keys);
+
+			const bulkSet = [];
+
+			followerCounts.forEach((count, idx) => {
+				const tid = tids[idx];
+				if (count > 0) {
+					bulkSet.push([`topic:${tid}`, {followercount: count}]);
+				}
+			});
+
+			await db.setObjectBulk(bulkSet);
+
+			progress.incr(tids.length);
+		}, {
+			batch: 500,
+		});
+	},
+};