There are a number of things which could affect this. The first is the speed of your PC - if it's slow some of the flash 7 ads may take over the processor. I use a borrowed PIII-600 at home (my PC lives on a different continent for another 3 weeks), and it's pushed almost to it's limit. Much slower and I wouldn't bother with snooker. Make sure that you have enough memory and HD space as well.
The next things are security related. Firstly you should be running at least SP1, and you should keep the patching up to date with Windows Update (very painful on a modem). Secondly you should run some kind of anti virus program, kept up to date with the latest virus definitions. There is a chance that you have a virus, worm or some other kind of intrusion on your system if you are not up to date. It is estimated that the maximum time needed for an unprotected PC on the internet to become infected is 25mins. If you run P2P software like Kazaa you are even more at risk without protection. It's also worth running anti-spyware software as they can sometimes slow the PC down. Ad-Aware (www.ad-aware.com) is free and fairly effective.
There are other things which can affect your PC. Is something else using the connection (are you sharing P2P files, for example)? Is your Java up to date? Can you see which process is using the CPU? etc.
