How to speed up Drupal 7 calls to _theme_process_registry? Using xhprof php profiler I can see there is much more then 100000 calls to function_exists 
each time user accesses a Drupal 7.8 page, mostly from _theme_process_registry.

What to do to limit the number of or cache these calls ?
I found there is already an issue related to this on drupal.org: Performance: optimize building theme registry by using get_defined_functions() instead of function_exists()