Anytime you use a proxy your web access is going to slow down. There is no getting around that. Somewhere along the line your proxy will slow your access regardless. And since the question is beyond what firefox does you should find a VPN or Proxy forum to ask those questions at as well.

Thank you for your reply, but I have to respectfully disagree. I had a subscription to Anonymizer for a long time. I am no longer able to access this feature nor is their website available, so I think they must have discontinued. During the time I was able to use their software, my browsing speed was not affected. Or if it was, it was negligible.

Put this way alot depends on where the Proxy or VPN is based from and the farther it is from your location there will be drop in speed because your going through their site and not directly to the site. Also some sites can and will block any Proxy or VPN when detected because they ping and it comes back and they will block accordingly. So unless your activity does no harm then just using internet as everyone else is just fine. If you really think they can't back track that is a false impression to have.