This game is really turning me mad

Don't know why but in certain kind of areas (snowy mountains in particular) if I'm riding my horse every few seconds the game has a sort of "pause", that seems to be caused by cell loading since I can see stuff appearing in the background when this happens.
The strange thing is that by foot (even sprinting as Usain Bolt) I don't get any kind of problem, but riding my horse at every speed cause this strange stuttering!
FPS is always 60 and I don't see any changes when the stuttering happens, the only thing changing is the VRAM usage...

I've already tried to remove all my mods and to let the launcher create default .ini files but no success... what's going on??

I've uploaded my last save to let you try: just climb to Helgen by horse and see what happens...
https://rapidshare.com/files/1700915183/quicksave.ess

No one? Any advices?

Don't ride a horse?

Sorry, sorry, I couldn't resist.

I used to get this in Oblivion, eventually fixed it by defragging, installing an "anti-stutter" mod and if I remember rightly, disabling my AV software helped a little bit too.

In oblivion this was caused by the sound of the horse steps being too strainful. A mod with more forgiving sound version or avoiding that sound (two versions) was made to fix that.

No idea if the cause is the same. I personally didn't experience this, but I ride really few times and I think I never done in 1.4.

Thanks for the help guys (especially GSJ1977 ), I'll try defragmenting my hdd... but the strange thing is that riding my horse around whiterun or riverwood (very gpu/cpu stressing) I don't get any problem, just in snowy places I get this stutter... really strange...

BTW amgepo do you know where I can find that mod? maybe I'll get it to work with skyrim somehow...

Yeah I still get this in some areas, horse only. Any tweak ever come around for this?

DId you bump your UgridsToLoad up by chance? If so to what?