I often have between 100 and 300 tabs open, across 20 or so windows.... I know it a lot, but I just never really exit web pages, why do it when you have 32gigs of ram and a quad-core 4.2ghz processor.... It doesn't even slow my computer down.
I've even tried opening around 300 tabs, then running 3 different virtual machines, each with a bunch of tabs open. Then running every program I have on my desktop on my main computer, and the virtual machines. Then I played Crysis, with no problem.