I tried this on my new zeroshell box because web browsing was painfully slow, even after I had disabled image scanning.
after following this procedure the proxy starts fine.
however there is absolutely no performance increase.
the proxy is still mind-numbingly slow.
I am running a p4 1500mhz with 128MB ram.
note: the only reason I am using the proxy is for the url blacklist, not the a/v scanning.