Efficiency of web proxy scripts vs. http proxy?

I was wondering which class would be more efficient: PHP (Glype, PHProxy), CGI (CGIProxy), or javascript based scripts that run on a webserver, or an http proxy run through squid. Assuming neither class was doing any caching, would one or the other be much more efficient at handling web browsing?

And how could I write a simple script to benchmark differences between the two?

Thanks!

From stackoverflow Lin

• By far, Squid; anything that requires running CGI or PHP will be much slower, because they require a process per request.

  From Mark Nottingham