My site is really screeching to a halt these days.  I took a look at /var/log/messages and it's full of errors all the time.

httpd: PHP Warning:  preg_split() [<a href='function.preg-split'>function.preg-split</a>]: Compilation failed: nothing to repeat at offset 8 in /home/public_html/extensions/SemanticMediaWiki/includes/SMW_QueryProcessor.php on line 805

is very common and

httpd: PHP Notice:  Undefined variable: info_id in /home/public_html/extensions/SemanticForms/includes/ on line 589

occurs sometimes.

My site is mixed English, Ancient Greek, Ancient Hebrew and Latin, so there's a lot of Unicode.  I haven't gone with the new MySQL charset

# Experimental charset support for MySQL 4.1/5.0.
$wgDBmysql5 = false;

Is this a fault of mine or SMW?