As you know, even if it is possible to start httpd in worker mode under CentOS/RedHat, php in default rpm repo is not thread-safe. And the default configuration for stability is mpm_prefork. So, two questions:
Is there PHP accelerator capable of working in mpm_prefork mode (using shm or whatever)?
If there is none, what can be done to improve PHP speed on CentOS/RedHat systems (I want to use rpms, preferably from default CentOS repo; building custom PHP from source code is not a good option for me)