There is only 2 ways two change your ip address
1. Spoofing -- and this does not work with damn anymore with the new style routers. Plus your ISP can still see what you are doing
2. Some form of a proxy server. And most of the free ones are slow. There are paid proxies that are not slow at all. But only one of the two does p2p (
www.anonx.com) I have been using them for less than a month and have been very happy with their performance.
As pointed out in a previous thread AnonX may not have enough users to max their system and hurt performance, yet. But, For now it works and I will pay month to month for it.