It does however cause my desktop to hang like a 21 day matured steak...
IE9, fast and sleek.
For me it goes:
IE9
Chrome
IE8
Opera
FF
Opera with Chrome as a last gasp choice if I have (rare) problems in Opera.
Also use all the major browsers at some point for testing reasons.
I use Opera by preference due to speed and how lightweight it is. However I have issues with Flash and incompatibility therefore always have Chrome open at the same time.
However Chrome doesn't save groups of sessions......