My firefox has 27 threads running. Though I realize you probably meant a thread per tab ( I don't know if it's in this nightly yet ). But even if all the tabs are a single thread, you'd still have separate threads for user interaction, networking, etc. A browser will usually be network limited before CPU limited anyway, except on low power processors. Separate threads for each tab would help on dual core atom.
So I have heard. And IE8 as well?
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