diff --git a/gazelle.sql b/gazelle.sql
index 40b96a24..f8f2e185 100644
--- a/gazelle.sql
+++ b/gazelle.sql
@@ -964,12 +964,6 @@ CREATE TABLE `stylesheets` (
   PRIMARY KEY (`ID`)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin;
 
-CREATE TABLE `subscribed_forums` (
-  `ForumID` int(10) NOT NULL,
-  `UserID` int(10) NOT NULL,
-  PRIMARY KEY (`ForumID`,`UserID`)
-) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin;
-
 CREATE TABLE `subscribed_users` (
   `UserID` int(10) NOT NULL,
   `SubscriberID` int(10) NOT NULL,
@@ -1619,6 +1613,12 @@ CREATE TABLE `users_sessions` (
   KEY `ActiveAgeKeep` (`Active`,`LastUpdate`,`KeepLogged`)
 ) ENGINE=InnoDB DEFAULT CHARSET=utf8;
 
+CREATE TABLE `users_subscribed_forums` (
+  `UserID` int(10) NOT NULL,
+  `ForumID` int(10) NOT NULL,
+  PRIMARY KEY (`UserID`,`ForumID`)
+) ENGINE=InnoDB DEFAULT CHARSET=utf8 COLLATE=utf8_bin;
+
 CREATE TABLE `users_subscriptions` (
   `UserID` int(10) NOT NULL,
   `TopicID` int(10) NOT NULL,
diff --git a/sections/forums/forum.php b/sections/forums/forum.php
index 5482f2b1..7a4aa75c 100644
--- a/sections/forums/forum.php
+++ b/sections/forums/forum.php
@@ -84,6 +84,11 @@
 	<div class="linkbox">
 <? if (check_forumperm($ForumID, 'Write') && check_forumperm($ForumID, 'Create')) { ?>
 		<a href="forums.php?action=new&amp;forumid=<?=$ForumID?>" class="brackets">New thread</a>
+<? } ?>
+<? if (!check_user_forum_subscription($UserID, $ForumID)) { ?>
+		<a href="forums.php?action=forum_subscription&amp;do=subscribe&amp;forumid=<?= $ForumID ?>" class="brackets" title="Automatically subscribe to new threads in this forum">Subscribe</a>
+<? } else { ?>
+		<a href="forums.php?action=forum_subscription&amp;do=unsubscribe&amp;forumid=<?= $ForumID ?>" class="brackets" title="Unsubscribe from new threads in this forum">Unsubscribe</a>
 <? } ?>
 		<a href="#" onclick="$('#searchforum').gtoggle(); this.innerHTML = (this.innerHTML == 'Search this forum' ? 'Hide search' : 'Search this forum'); return false;" class="brackets">Search this forum</a>
 		<div id="searchforum" class="hidden center">
diff --git a/sections/forums/functions.php b/sections/forums/functions.php
index 3b8e0bbe..f6de1173 100644
--- a/sections/forums/functions.php
+++ b/sections/forums/functions.php
@@ -23,7 +23,7 @@ function get_thread_info($ThreadID, $Return = true, $SelectiveCache = false, $Ap
 			if (!$ApiCall) {
 				error(404);
 			} else {
-				return NULL;
+				return null;
 			}
 		}
 		$ThreadInfo = $DB->next_record(MYSQLI_ASSOC, false);
@@ -139,3 +139,196 @@ function get_forums() {
 	}
 	return $Forums;
 }
+
+/**
+ * Add a forum subscription for the provided user id
+ *
+ * @param $UserID
+ * @param $ForumID
+ */
+function add_subscribed_forum($UserID, $ForumID) {
+	global $DB;
+
+	$UserID = (int)$DB->escape_str($UserID);
+	$Subscriptions = get_subscribed_forums($UserID);
+	if (!in_array($ForumID, $Subscriptions)) {
+		$Subscriptions[] = $ForumID;
+		$DB->query("INSERT INTO users_subscribed_forums (UserID, ForumID) VALUES ({$UserID}, $ForumID)");
+		cache_forum_subscriptions($UserID, $Subscriptions);
+	}
+
+	// Populate the aggregate forum subscription cache
+	$ForumSubscriptions = get_subscriptions_for_forum($ForumID);
+	if (!in_array($UserID, $ForumSubscriptions)) {
+		$ForumSubscriptions[] = $UserID;
+		cache_aggregate_forum_subscriptions($ForumID, $ForumSubscriptions);
+	}
+}
+
+/**
+ * Remove a forum subscription from the specified user id
+ *
+ * @param $UserID
+ * @param $ForumID
+ */
+function remove_subscribed_forum($UserID, $ForumID) {
+	global $DB;
+
+	$UserID = (int)$DB->escape_str($UserID);
+	$Subscriptions = get_subscribed_forums($UserID);
+	if (($key = array_search($ForumID, $Subscriptions)) !== false) {
+		$DB->query("DELETE FROM users_subscribed_forums WHERE ForumID = $ForumID AND UserID = {$UserID}");
+		unset($Subscriptions[$key]);
+		cache_forum_subscriptions($UserID, $Subscriptions);
+	}
+
+	$ForumSubscriptions = get_subscriptions_for_forum($ForumID);
+	if (($key = array_search($UserID, $ForumSubscriptions)) !== false) {
+		unset($ForumSubscriptions[$key]);
+		cache_aggregate_forum_subscriptions($ForumID, $ForumSubscriptions);
+	}
+}
+
+/**
+ * Get a list of forum subscriptions for the given user id
+ *
+ * @param $UserID
+ *
+ * @return array|int List of forum ids the user has subscribed to
+ */
+function get_subscribed_forums($UserID) {
+	global $Cache, $DB;
+
+	if (!$Subscriptions = $Cache->get_value("forum_subscriptions_{$UserID}")) {
+
+		$UserID = (int)$DB->escape_str($UserID);
+		$DB->query("SELECT * FROM users_subscribed_forums WHERE UserID = $UserID");
+		$ResultSet = $DB->to_array();
+
+		$Subscriptions = array();
+		foreach ($ResultSet as $Subscription) {
+			$Subscriptions[] = $Subscription['ForumID'];
+		}
+
+		cache_forum_subscriptions($UserID, $Subscriptions);
+
+	}
+
+	return $Subscriptions;
+}
+
+/**
+ * Wrapper method to pull the global requirement on $Cache out of above methods which should
+ * enable simpler unit testing
+ *
+ * @param $UserID
+ * @param $Subscriptions
+ */
+function cache_forum_subscriptions($UserID, $Subscriptions) {
+	global $Cache;
+
+	$Cache->set("forum_subscriptions_{$UserID}", $Subscriptions);
+}
+
+/**
+ * Returns true if the user is subscribed to the given forum id; otherwise false
+ *
+ * @param $UserID
+ * @param $ForumID
+ *
+ * @return bool
+ */
+function check_user_forum_subscription($UserID, $ForumID) {
+	$Subscriptions = get_subscribed_forums($UserID);
+	if (in_array($ForumID, $Subscriptions)) {
+		return true;
+	} else {
+		return false;
+	}
+}
+
+/**
+ * Returns a list of users subscribed to the given forum id
+ *
+ * @param $ForumID
+ *
+ * @return array|int List of user ids subscribed to the forum
+ */
+function get_subscriptions_for_forum($ForumID) {
+	global $Cache, $DB;
+
+	if (!$Subscriptions = $Cache->get_value("forum_subscriptions_forum_{$ForumID}")) {
+		$DB->query("SELECT * FROM users_subscribed_forums WHERE ForumID = $ForumID");
+		$ResultSet = $DB->to_array();
+
+		$Subscriptions = array();
+		foreach ($ResultSet as $Subscription) {
+			$Subscriptions[] = $Subscription['UserID'];
+		}
+		cache_aggregate_forum_subscriptions($ForumID, $Subscriptions);
+	} else {
+		$Subscriptions = $Subscriptions;
+	}
+
+	return $Subscriptions;
+}
+
+/**
+ * Wrapper method to pull the global requirement on $Cache out of above methods which should
+ * enable simpler unit testing
+ * @param $ForumID
+ * @param $Subscriptions
+ */
+function cache_aggregate_forum_subscriptions($ForumID, $Subscriptions) {
+	global $Cache;
+
+	$Cache->set("forum_subscriptions_forum_{$ForumID}", $Subscriptions);
+}
+
+/**
+ * Updates the subscriptions_user_* cache entry to add the given topic ID
+ * for the specified user
+ * @param $UserID
+ * @param $TopicID
+ */
+function add_topic_subscription_for_user($UserID, $TopicID) {
+	global $Cache;
+
+	$Subscriptions = get_topic_subscriptions_for_user($UserID);
+	if (!in_array($TopicID, $Subscriptions)) {
+		$Subscriptions[] = $TopicID;
+	}
+
+	cache_topic_subscriptions_for_user($UserID, $Subscriptions);
+}
+
+/**
+ * Returns a list of topic ids the user is subscribed to
+ * @param $UserID
+ *
+ * @return array|int
+ */
+function get_topic_subscriptions_for_user($UserID) {
+	global $Cache, $DB;
+
+	if (!$Subscriptions = $Cache->get_value("subscriptions_user_$UserID")) {
+		$DB->query("SELECT TopicID FROM users_subscriptions WHERE UserID = $UserID");
+		$ResultSet = $DB->to_array();
+
+		$Subscriptions = array();
+		foreach ($ResultSet as $TopicID) {
+			$Subscriptions[] = $TopicID;
+		}
+
+		cache_topic_subscriptions_for_user($UserID, $Subscriptions);
+
+	}
+
+	return $Subscriptions;
+}
+
+function cache_topic_subscriptions_for_user($UserID, $Subscriptions) {
+	global $Cache;
+
+	$Cache->set("subscriptions_user_$UserID", $Subscriptions);
+}
\ No newline at end of file
diff --git a/sections/forums/index.php b/sections/forums/index.php
index 71260d54..af9bd1f0 100644
--- a/sections/forums/index.php
+++ b/sections/forums/index.php
@@ -108,8 +108,8 @@
 		case 'warn':
 			require(SERVER_ROOT.'/sections/forums/warn.php');
 			break;
-		case 'forum_subscribe':
-			include('subscribe.php');
+		case 'forum_subscription':
+			include('subscription.php');
 			break;
 		default:
 			error(404);
diff --git a/sections/forums/subscribe.php b/sections/forums/subscribe.php
deleted file mode 100644
index 7c471809..00000000
--- a/sections/forums/subscribe.php
+++ /dev/null
@@ -1,14 +0,0 @@
-<?php
-
-ini_set('display_errors', '1');
-authorize();
-
-$ForumID = db_string($_GET['forumid']);
-if ($_GET['perform'] == 'add') {
-	$DB->query("INSERT IGNORE INTO subscribed_forums (ForumID, SubscriberID) VALUES ('$ForumID', '$LoggedUser[ID]')");
-} elseif ($_GET['perform'] == 'remove') {
-	$DB->query("DELETE FROM subscribed_forums WHERE ForumID = '$ForumID' AND SubscriberID = '$LoggedUser[ID]'");
-}
-header('Location: forums.php?action=viewforum&forumid=' . $ForumID);
-?>
-
diff --git a/sections/forums/subscription.php b/sections/forums/subscription.php
new file mode 100644
index 00000000..fb5e46b0
--- /dev/null
+++ b/sections/forums/subscription.php
@@ -0,0 +1,16 @@
+<?php
+
+if (!check_forumperm($ForumID)) {
+	error(403);
+}
+
+$ForumID = (int)db_string($_GET['forumid']);
+$Subscriptions = get_subscribed_forums($LoggedUser['ID']);
+if ($_GET['do'] == 'subscribe') {
+	add_subscribed_forum($UserID, $ForumID);
+} elseif ($_GET['do'] == 'unsubscribe') {
+	remove_subscribed_forum($UserID, $ForumID);
+}
+header('Location: forums.php?action=viewforum&forumid=' . $ForumID);
+?>
+
diff --git a/sections/forums/take_new_thread.php b/sections/forums/take_new_thread.php
index bdd4e50d..ada36e04 100644
--- a/sections/forums/take_new_thread.php
+++ b/sections/forums/take_new_thread.php
@@ -90,31 +90,28 @@
 		LastPostTime     = '".sqltime()."'
 	WHERE ID = '$TopicID'");
 
-if (isset($_POST['subscribe'])) {
-	$DB->query("
-		INSERT INTO users_subscriptions
-		VALUES ($LoggedUser[ID], $TopicID)");
-	$Cache->delete_value('subscriptions_user_'.$LoggedUser['ID']);
+// Do a bulk insert into the users_subscriptions table for all users
+// subscribed to this forum
+$Subscribers = get_subscriptions_for_forum($ForumID);
+if (count($Subscribers) > 0) {
+	$SubscribersValueString = '(';
+	$SubscribersValueString .= implode(", $TopicID), (", $Subscribers);
+	$SubscribersValueString .= ", $TopicID)";
+	$DB->query("INSERT INTO users_subscriptions (UserID, TopicID) VALUES $SubscribersValueString");
 }
 
-//auto subscribe
-/*
-if (check_perms('users_mod')) {
+// Loop through all the users that got subscribed to the thread and
+// update the cache entries
+foreach($Subscribers as $Subscriber) {
+	add_topic_subscription_for_user($Subscriber, $TopicID);
+}
+
+if (isset($_POST['subscribe']) && !in_array($LoggedUser['ID'], $Subscribers)) {
 	$DB->query("
-		SELECT SubscriberID
-		FROM subscribed_forums
-		WHERE ForumID = '$ForumID'
-			AND SubscriberID != '$LoggedUser[ID]'");
-	while (list($SubscriberID) = $DB->next_record()) {
-		$DB->query("INSERT INTO users_subscriptions VALUES ($SubscriberID, $TopicID)");
-		//	$DB->query("INSERT INTO forums_last_read_topics
-			//						(UserID, TopicID, PostID) VALUES
-				//							('$SubscriberID', '".$TopicID ."', '".db_string($PostID)."')
-					//							ON DUPLICATE KEY UPDATE PostID='$LastPost'");
-		$Cache->delete_value('subscriptions_user_'.$SubscriberID);
-	}
+		INSERT INTO users_subscriptions
+		VALUES ($LoggedUser[ID], $TopicID)");
+	add_topic_subscription_for_user($LoggedUser['ID'], $TopicID);
 }
-*/
 
 if (empty($_POST['question']) || empty($_POST['answers']) || !check_perms('forums_polls_create')) {
 	$NoPoll = 1;