diff --git a/scripts/createsim.php b/scripts/createsim.php
index e0b5fc906b..d97ecc1c4d 100644
--- a/scripts/createsim.php
+++ b/scripts/createsim.php
@@ -20,8 +20,8 @@
 
 define('INSTALLDIR', realpath(dirname(__FILE__) . '/..'));
 
-$shortoptions = 'u:n:b:t:x:';
-$longoptions = array('users=', 'notices=', 'subscriptions=', 'tags=', 'prefix=');
+$shortoptions = 'u:n:b:g:j:t:x:z:';
+$longoptions = array('users=', 'notices=', 'subscriptions=', 'groups=', 'joins=', 'tags=', 'prefix=');
 
 $helptext = <<<END_OF_CREATESIM_HELP
 Creates a lot of test users and notices to (loosely) simulate a real server.
@@ -29,6 +29,8 @@ Creates a lot of test users and notices to (loosely) simulate a real server.
     -u --users         Number of users (default 100)
     -n --notices       Average notices per user (default 100)
     -b --subscriptions Average subscriptions per user (default no. users/20)
+    -g --groups        Number of groups (default 20)
+    -j --joins         Number of groups per user (default 5)
     -t --tags          Number of distinct hash tags (default 10000)
     -x --prefix        User name prefix (default 'testuser')
 
@@ -49,6 +51,18 @@ function newUser($i)
     }
 }
 
+function newGroup($i)
+{
+    global $groupprefix;
+
+    $user = User_group::register(array('nickname' => sprintf('%s%d', $groupprefix, $i),
+                                       'local'    => true,
+                                       'fullname' => sprintf('Test Group %d', $i)));
+    if (!empty($user)) {
+        $user->free();
+    }
+}
+
 function newNotice($i, $tagmax)
 {
     global $userprefix;
@@ -117,38 +131,89 @@ function newSub($i)
     $to->free();
 }
 
-function main($usercount, $noticeavg, $subsavg, $tagmax)
+function newJoin($u, $g)
+{
+    global $userprefix;
+    global $groupprefix;
+
+    $userNumber = rand(0, $u - 1);
+
+    $userNick = sprintf('%s%d', $userprefix, $userNumber);
+
+    $user = User::staticGet('nickname', $userNick);
+
+    if (empty($user)) {
+        throw new Exception("Can't find user '$fromnick'.");
+    }
+
+    $groupNumber = rand(0, $g - 1);
+
+    $groupNick = sprintf('%s%d', $groupprefix, $groupNumber);
+
+    $group = User_group::staticGet('nickname', $groupNick);
+
+    if (empty($group)) {
+        throw new Exception("Can't find group '$groupNick'.");
+    }
+
+    if (!$user->isMember($group)) {
+        $user->joinGroup($group);
+    }
+}
+
+function main($usercount, $groupcount, $noticeavg, $subsavg, $joinsavg, $tagmax)
 {
     global $config;
     $config['site']['dupelimit'] = -1;
 
     $n = 1;
+    $g = 1;
 
     newUser(0);
+    newGroup(0);
 
     // # registrations + # notices + # subs
 
-    $events = $usercount + ($usercount * ($noticeavg + $subsavg));
+    $events = $usercount + $groupcount + ($usercount * ($noticeavg + $subsavg + $joinsavg));
+
+    $ut = $usercount;
+    $gt = $ut + $groupcount;
+    $nt = $gt + ($usercount * $noticeavg);
+    $st = $nt + ($usercount * $subsavg);
+    $jt = $st + ($usercount * $joinsavg);
 
     for ($i = 0; $i < $events; $i++)
     {
-        $e = rand(0, 1 + $noticeavg + $subsavg);
+        $e = rand(0, $events);
 
-        if ($e == 0) {
+        if ($e > 0 && $e <= $ut) {
+            printfv("Creating user $n\n");
             newUser($n);
             $n++;
-        } else if ($e < $noticeavg + 1) {
+        } else if ($e > $ut && $e <= $gt) {
+            printfv("Creating group $g\n");
+            newGroup($g);
+            $g++;
+        } else if ($e > $gt && $e <= $nt) {
+            printfv("Making a new notice\n");
             newNotice($n, $tagmax);
-        } else {
+        } else if ($e > $nt && $e <= $st) {
+            printfv("Making a new subscription\n");
             newSub($n);
+        } else if ($e > $st && $e <= $jt) {
+            printfv("Making a new group join\n");
+            newJoin($n, $g);
         }
     }
 }
 
-$usercount  = (have_option('u', 'users')) ? get_option_value('u', 'users') : 100;
-$noticeavg  = (have_option('n', 'notices')) ? get_option_value('n', 'notices') : 100;
-$subsavg    = (have_option('b', 'subscriptions')) ? get_option_value('b', 'subscriptions') : max($usercount/20, 10);
-$tagmax     = (have_option('t', 'tags')) ? get_option_value('t', 'tags') : 10000;
-$userprefix = (have_option('x', 'prefix')) ? get_option_value('x', 'prefix') : 'testuser';
+$usercount   = (have_option('u', 'users')) ? get_option_value('u', 'users') : 100;
+$groupcount  = (have_option('g', 'groups')) ? get_option_value('g', 'groups') : 20;
+$noticeavg   = (have_option('n', 'notices')) ? get_option_value('n', 'notices') : 100;
+$subsavg     = (have_option('b', 'subscriptions')) ? get_option_value('b', 'subscriptions') : max($usercount/20, 10);
+$joinsavg    = (have_option('j', 'joins')) ? get_option_value('j', 'joins') : 5;
+$tagmax      = (have_option('t', 'tags')) ? get_option_value('t', 'tags') : 10000;
+$userprefix  = (have_option('x', 'prefix')) ? get_option_value('x', 'prefix') : 'testuser';
+$groupprefix = (have_option('z', 'groupprefix')) ? get_option_value('z', 'groupprefix') : 'testgroup';
 
-main($usercount, $noticeavg, $subsavg, $tagmax);
+main($usercount, $groupcount, $noticeavg, $subsavg, $joinsavg, $tagmax);