lighttpd and phpadnews

[pointers]

Hi,
I am using lighttpd for just image serving purpose and it runs really fast. We have an ad-server using phpadnews but
apache causes very high load on the server. If you have any experience on lighttpd with php or what others on the world
use for ad-server .
I have made all performance increments and I am using virtual server to distribute load into three servers.
There are totally 1400-1500 active connections and this connection is distributed into the servers (P4 3GHZ 2GB mem)
and this causes load from 20 to 150 and response times are getting slower.

When apache was causing high load on image serving I have replaced it with lighttpd and no problem with it. I wonder how I will get a performance increment with lighttpd enabled with php on a phpadnews ad server.

I will make a test but before that, I just would like to get your opinions.


Kind Regards