There was also a recent post regarding having large numbers of tabs open in Firefox (see https://news.ycombinator.com/item?id=14823807) and it did pretty well.
Much more streamlined UI, and much faster. I already preferred Firefox because of better handling of large numbers of tabs, but Nightly beats Chrome even at smaller number of tabs so far (I synced my FF account so my extensions, etc got reproduced, and I manually replaced legacy ones with newer ones). I still have to see how it holds up over a period of use, but so far with my data synced it looks great.
However it still seems to lack in the animation department. CSS transformations and transitions, particularly if affecting complex elements, just aren't as smooth as in Chrome or Safari. Your own menu animations, like the global drop down menu, are finally fluid and smooth though.
BLAZING >>>>>>> FAST