I was finding big problems with searches - looked like it was in some kind of loop when going against com_search. But - there's no option in the config to disable it. So, I patched
components/com_sef/joomsef.php - line 492 or thereabouts, to read:
case (in_array($option, $sefConfig->skip) || $option=="com_search")
This will then explicitly skip com_search...
A bit of a quick n' dirty hack - but maybe a better one will find its way into the component?