The 29.42 drivers are compatible with CSF3 - Whitey had a config problem which he later discovered.
As to why they appear to produce improved frame rates is anybody's guess.
NVidia produce drivers as often as I have breakfast.
They're famous for it.
What tends to happen is that they discover that an element of any given release doesn't work happily with a particular game. So they release a new driver that fixes it. This often results in problems with a different game that may have worked fine previously. (The inability to display the menu bar in full screen mode in FS2002 with a driver released a few months ago, whose number I forget, springs to mind.) So then they release a driver update to fix that and something else doesn't work...and so on...and so on...
This is a slightly oversimplistic view but you get the idea.