Using FireFox 3.6 and all the pages take a long long time to load.
Same here, also with FireFox 6. This has been going on for many months, mostly in the morning and afternoons (Central time).
As WinCustomize tries load if I hit the back arrow and the the forward arrow it usually loads right away.
I have a high speed broadband connection (ethernet) and connect at around 83 Mb/s.