While I browsed I tried to figure out how to make the experience faster. I tried disabling Java Script, and that didn't work. Finally I disabled the automatic loading of images. It worked! If you chug along on these boards just disable automatic image loading while you browse them. In line images are against the rules anyway right? All you lose are the avatars and emoticons.
At the least this worked for Firefox. Even on that old 1Ghz I can browse fine now.
I suppose this may be of little use to many people, but who knows maybe it will help someone. I've never encountered a message board that slowed lagged graphically on scrolling before this one, but hopefully this simple workaround helps others. Something about the image layout must stress older computers. I figure posting this may help someone else, if it hasn't been said already.