If you use a web proxy.. the free version of
http://www.hidemyass.com, then performance is not great and service can be unstable.
If you always need to by-pass sillypore's Internet filters (so much for freedom of information), then the better choice would be using a Virtual Private Network (VPN).
I'm using the paid VPN service of hidemyass.com as I am in China. But there are free alternatives. I liked AnchorFree's Hotspot Shield VPN. Been using for a while until I needed some additional features. For most purposes, it will work fine. Check it out and download the small client software :
http://anchorfree.com/downloads/hotspot-shield/
Hope that helps. Cheers.