I'm using Apache + PHP with default config on CentOS 5. I increased only prefork connections. The server has over 10000 connections on port 80. The server hosts mobile sites and all pages load ads from another server (with PHP curl).
My server config: - Intel e3 -1270 (2x4x3.4GHZ) - 16 gb ram - 2 tb hdd with raid10
Average load between 1 to 2
The main problem is when a site loads ads from another server then pages will take a long time to open.
I'm also using CSF firewall. I have also tried nginx (frontend nginx, backend apache).