I have the same problem.
On my Nvidia card it runs very sluggish in fullscreen mode.
The newest driver is installed.
Did you additionally change the configuration file of winspmbt ? I have tried several options but it won't run as smooth as in Windows XP. LCD Scaling works (resolution is 800x600 as it should be).
No, I didn't change anything in the configuration file.
On slow downs: It does seem to run just a bit slower, but not really noticeable. The only thing I noticed was that fullscreen seems to use a lot more CPU for some reason. My fans run at their normal speed when playing windowed, but fullscreen they rev up to keep everything cool.