As far as Firefox being state of the art, give me a fucking break. They've been working on multi-threaded FF (Electrolysis) for going on 6 years now, and every time it gets force-enabled in FF Nightly it breaks _EVERYTHING_:
UserScript (Greasemonkey), broken
TreeStyleTabs, mostly broken
RequestPolicy - and every other extension of its ilk, completely borked.
The only thing it appears to do, is make it "seem like" FF is responsive, except it still takes just as long to load a large session. Except all the tabs just say "New Tab" for ages, until they actually get their title.
Now the one thing that e10s (Electrolysis) CAN do, is close a window without locking up every FF window for an extended period of time.
So FF seems like it is responsive, but that's just a sham. It just isn't "not responding" during the time while it loads a large session. I have tabs loaded in the background, so only the single tab in a given window needs to actually be loaded, yet it still takes 5-10 minutes to load a large session (restore their title, favicon, and tab position). WTF.
Mozilla expenses for software development in 2012 was almost $150,000,000. --- does that sound like "small development team" to you?