[Andreas]

The Template is not the Problem, can be done with a Plugin.

Hook: forumbit_display

PHP Code:

if ($forum['link'])
{
    $forum['replycount'] = '';
    $forum['threadcount'] = '';
    eval('$forum[\'lastpostinfo\']  = "' . fetch_template('linkhits') . '";');
} 


This kicks off 1 File edit.

However, getting the count doesn't seem to be possible without the File edit.
The other Option would be to use a Query. But this would add 1 Query to Forumhome and every forumdisplay.php call where the Forum being displayed contains sub-forums that are links.
Or the Forumcache would have to be rebuild upon every Hit, which is even worse IMHO.

However, some furhter suggestions:

Your Counter-Update seems to be run every Time smth. is being done in ACP?
I'd suggest to get rid of the Settings and the admin_global Plugin.
Instead, make a new control in Forum Manager that shows the current Value so the User can just input it's own.

Hook: forumdata_start

PHP Code:

$this->validfields['linkhits'] = array(TYPE_UINT, REQ_NO); 


Hook: forumadmin_edit_form

PHP Code:

if (trim($forum['link'] != ''))
{
    $check = $db->query_first("SELECT linkhits FROM " . TABLE_PREFIX . "forum WHERE forumid = $forum[forumid]");
    print_table_header('Forum Link Hit Counter');
    print_input_row('Hit Counter Value<dfn>Here you can manually adjust the Hit-Counter for this Forum-Link</dfn>', 'forum[linkhits]', $check['linkhits']);
} 


The check-query isn't ideal, but necessary as the Forum Manager displays cached Data

Don't execute the Update in Global-Start, as this causes 1 additional Query for every Forum being displayed, no matter if it is a Link or not.

Hook: header_redirect

PHP Code:

global $foruminfo;
if (trim($foruminfo['link']) != '')
{
    $vbulletin->db->query("UPDATE " . TABLE_PREFIX . "forum SET linkhits = linkhits +1 WHERE forumid=$foruminfo[forumid]");
} 


You should also cache the Template on forumdisplay, as it might be shown here too.

Hook: cache_templates

PHP Code:

if (THIS_SCRIPT == 'index' OR THIS_SCRIPT == 'forumdisplay')
{
    $globaltemplates  = array_merge($globaltemplates, array('linkhits'));
}