Internet speed was the only major problem area I thought of that you didn't mention, and, since it can be that major, I thought I'd add it. Dial-up is inherently slow, and can slow down even more at times. Also dial-up magnifies any other server problems, such as the ad server slowness. WiFi connections are usually faster than dial-up, but the speed varies immensely because of signal strength and amount of traffic sharing the bandwidth. I've actually had WiFi that was slower at times than dial-up because of both the above issues.

Things like memory, processor type and speed, and OS can be important in diagnosing some problems, but in this case internet connection and the other things you mentioned are more likely, with the problems reported.

The only reason I mentioned the free vs. paid FT, is I always watch the bottom of the Firefox window to see what specific site is taking so long to load, and lately (since the last major sluggishness that everyone experienced) the only times I see a major problem it's always during the loading of the ads, so you may very well be onto something there.

Too much Flash in IE or Firefox is also a major problem, both on loading time and on system resources. If I have too many flash items open (ads and/or real content) my computer slows down to a crawl, although I usually have upwards of 150 tabs total opened, in several browser windows, most of the time (presently I only have 65 tabs in this window and a total of 89 in 4 Ff and 2 IE windows, a very small number for me). That's why I use FlashBlock on Firefox, unfortunately IE7 doesn't have that add-on available.