Just wanted to update the performance stats for my nVidia card when using the proprietary drivers in Fedora 14.
direct rendering: Yes
OpenGL renderer string: GeForce4 MX 4000/AGP/SSE2
GtkPerf 0.40 - Starting testing: Sat Jan 14 00:53:20 2012
GtkEntry - time: 0.07
GtkComboBox - time: 1.96
GtkComboBoxEntry - time: 2.56
GtkSpinButton - time: 0.24
GtkProgressBar - time: 0.21
GtkToggleButton - time: 0.28
GtkCheckButton - time: 0.19
GtkRadioButton - time: 0.27
GtkTextView - Add text - time: 0.47
GtkTextView - Scroll - time: 0.38
GtkDrawingArea - Lines - time: 1.71
GtkDrawingArea - Circles - time: 1.73
GtkDrawingArea - Text - time: 0.67
GtkDrawingArea - Pixbufs - time: 0.52
Total time: 11.26
It's better than nouveau but overall, not significantly better.
With F14 and the proprietary nVidia drivers, and running Firefox 8.0 that I downloaded a couple of months ago from Remi repos, FF is lightning fast, with no choppiness or delays of any kind.
Next, I'll try to find this exact version of Firefox (8.0) and test that with F16 + the nouveau drivers.
No, I haven't given up quite yet.