Hi Polonus,
thanks, I already read your post there
The thing is even if speed is still not there, FF4 is quite promising, it already beats all the rest with D2D (hardware acceleration) on HTML5, twice as fast IE9 preview on MS own test found here:
http://ie.microsoft.com/testdrive/. Second is Opera and last,
like 8 times slower then FF4.0b1, comes Google Chrome...
They will implement JaegerMonkey later this year, that could bring speed on FF on par with Chrome and Opera.
As to Flock, from what I read they're definitely switching to Webkit, so you won't have much choice but go back to Firefox.