Box optimization for proxies

I am just wondering, what is the suggested numbers to make for apache, php, etc.


The box I am referring to being made is:
Intel 2.6GHz Processor
512MB RAM

The suggested optimization area would be apache (Currently):

Timeout 4000
KeepAlive On
MaxKeepAliveRequests 500
KeepAliveTimeout 15
<IfModule prefork.c>
MinSpareServers 5
MaxSpareServers 10
StartServers 5
MaxClients 256
MaxRequestsPerChild 0
</IfModule>


Does anyone have any suggestions for optimization? I have read a few guides, but most are for 'general optimization', and as we all know, proxies need a different perspective.

If anyone else knows any PHP optimization techniques as well, I am keen to hear those as well!

Any helpful answers will be +3rep.