bbpress taking LONG time to load and PHP warning


I have enabled the group forums from BuddyPress menu and it takes almost 30 seconds for the forums page to load and quite often it loads page without the css definitions. (text only displays).

In my server logs, I see this:

PHP Warning: mysql_set_charset() expects parameter 2 to be resource, boolean given in /home/guplogs/html/wp-includes/wp-db.php on line 553, referer: **********/groups/gl-support/

any clues?