The binary drivers or the nouveau ones? I've always used the binary ones, and Nvidia's driver quality has been why I've only bought Nvidia cards for many years. It has only been this release that caused me problems, and even then I finally solved them by downgrading the Nvidia driver version.
I tried gtkperf to see what figures I get. I did note that the results depend on the size of the window quite a bit.
On my workstation with an 8800GT I got 3.46 seconds at default window size and 4.08 at 1920x1200 (using mutter window manager). On my 5 year old laptop with Intel 965 graphics I got 7.30 seconds (using metacity).
I switched to Chrome years ago and its tab switching is fine.
The performance sucks and the gtkperf shows it
Running gtkperf on a laptop with a 943/940gml integrated graphics card Total time: 7.17
On a laptop with a nvidia 8400 card Total time: 9.08
eeepc 701sd Total time: 25.31
Nothing has changed, while 3D is decent, 2D drawing is a pain, just switching tabs in firefox makes you want to throw the damn thing out the window.