have nearly same issue on my intel iMac , website load slower especially if they have pictures (for example ebay) taking ages to load them ,
and its not hardware related in any way so not faulty or wrong setup router and not a airport or ethernet problem on the iMac
and my PPC Mac's running osx tiger work fine and as i have a second partition on the iMac intel running osx tiger too because of apple talk
and there the same sites load nearly instantly including pictures
so it has to be a snow leopard problem of some sort
Maybe I was not clear: yes, it is related to Mac OS X and not hardware and switching IP Flood Protecion/Firewall/DoS off helped in my case. I don't understand why but it did the trick.
Just give it a go.
How do I know it is software related? The same iMac have never had any problems and after one of system updates it started to struggle to open web pages. Again: the same particular iMac therefore the same piece hardware.
I'm not saying it will help you but why not try?