yeah actually mpm-worker performs far better than mpm-prefork.
For fastest speed the mpm-event is recommended.
But the speed improvements are related to static file transfers.
Php won't get faster with fastcgi - but much more secure - because of the use of suexec (and later chroot
)
The speed of php-fastcgi against mod_php is perhaps 90-95% so fastcgi is a bit slower.
But this is nothing compared to other options like suphp (php will be executed as cgi on every call (10-15% of mod_php's speed
).
So fastcgi is the best choice between speed and security.
A small drawback atm is that somehow apache needs a lot of ram to work - but this could be related to some settings for the worker module - we're investigating that