Our new D7 site was running very slowly so I did some profiling with devel/xhprof and found that D7 was doing millions of preg_grep function calls within drupal_find_theme_functions() in theme.inc. This happened on every page load.
It's my understanding that the drupal_find_theme_functions function should only be called when the theme registry is being rebuilt - am I correct in that?
I made sure that "rebuild theme registry" was off in devel, and then disabled devel entirely. However, I'm still seeing those millions of function calls to preg_grep in drupal_find_theme_functions on every page load (I added a piece of code to theme.inc to log when the function was called).
We're using a theme based on Omega and if we are rebuilding the theme registry each time I'm not seeing how/why it's happening. We're turning off as many contrib modules as we can in the meantime. Any help/advice would be MUCH appreciated!!