I have very similar problem. My game was always running smoothly in the past. But yesterday I went to Kohan after some time and I was rather shocked by its very poor performance. Just as DJBoo describes. Lately I discovered very strange thing: when I move mouse, the game stucks, when I stop, game runs. This is actually very strange and I don`t have any issues with my other games, so I have no idea what is wrong here.

Thanks to any ideas...

Same issue here with Win7 64-bit - Ati Radeon Mobility. Game performs ok, when the mouse is not moving - but as soon as I pan the screen with the mouse, there is a large graphical lag - so the game becomes almost unplayable. I've tried all the above steps also without any success.

Well I seem to have cured it... rather than attempt a driver update for my graphics card through AMD's support site (where the latest drivers don't support my hardware apparently) I opened Device Manager and asked Windows 7 to update the Display Adapter. It was an Ati Mobility Radeon HD 5400 Series, and after Windows had identified the card as a Mobility Radeon HD 5470 and installed new drivers, I rebooted and then the game runs smooth without any graphics lag when the mouse is being moved.

All of the fiddling done previously was reset, before I did this - Compatibility mode, DEP, the command line option -FixLogitech - and it was the simple Windows update my driver for me option that seemed to work - so give it a try if all else has failed for you.

Nice try, but doesn`t work for me... :/ My Windows said that driver is already actual and didn`t change anything.

Kudos from me , for what you ask? just amazed someone replied to this thread after 1.1 years LOL, LOUD!?!?!?

I used to have such problems with poor fps in Kohan II. It's generally a video driver issue - however, in my case, it wasn't the actual video driver at fault, but a program called "ASUS Gamer OSD" (look for it in your Control Panel under Programs and Features).

If you have this Gamer OSD installed you need to uninstall it because it conflicts with the video card drivers. The conflict caused by this program actually decreases graphical performance in *all* of your games, it's only most noticable in games like Kohan II and Sid Meier's Pirates where the fps drops to unplayably low levels because of it.

Once you uninstalled the Gamer OSD, reboot your machine and things should be fine. If not, then reinstall the video card drivers too just to be safe.

As for the belated response - I guess it's better late than never. :) Others might run into this issue and come here looking for solutions. I'm posting this for them (if nothing else), hoping it will help someone out. :)