I can't think of any good ones off hand - I've not used any in a while, as my connection has been fine recently.
Some info, anyway:
Thread on how to change proxy -
http://www.cableforum.co.uk/board/showthread.php?t=8783
List of NTL proxies -
http://homepage.ntlworld.com/robin.d...cache.html#ntl
Robin Walker's proxy info page -
http://homepage.ntlworld.com/robin.d...trancache.html
What do you mean by slow, by the way? Is everything slow? How slow is slow? etc.
Have you tried any speed tests?
Robin Walker's Simple Speed Test -
http://homepage.ntlworld.com/robin.d...speedtest.html
Dan Elwell's speed test prog -
http://www.broadbandspeedtest.net/
Also, what's your location? (the NTL tech people here may find that useful)