Difficulty browsing 2+2 smoothly

[Tablerat]

I'm having difficulty browsing 2+2 smoothly and quickly on my home browser (Firefox latest upgrade). Whether or not I'm logged in, I'll click a forum or post and about 25% of the time, only the menu on the left remains and the rest of the page is white, and the browser shows "done" at the bottom, so there's no delay or time out.

The only other site I have problems with is mapquest.com, but I don't frequent many sites. Sometimes a weird script like page will pop up when I click a link on mapquest, but that hasn't occurred here recently.

I regularly clean my cache and cookies and temp files. I use AVG antivirus, ZoneAlarm Pro firewall if that helps.

I am mostly useless with computers, so that's why I'm asking here first, and also to see if anyone else has had a similar problem before. Thanks.