With a standard prefork install apache is decently fast on my machine, pumping out around 5MB/s.

But when I recompile with PHP FPM its quite slow (1.5-2 MB/s). Ive tried tuning the server event MPM in all different ways with no benefit.

I wouldnt expect such a striking difference between the two. Has anyone noticed this? Any suggestions on how to diagnose the issue?