Problem I have is that I can fix it by turning vsync on again, but if I do that I have mouse lag in all menus instead. bMouseAcceleration=0 doesn't work for me. I need the vsync off for the mouse lag to disappear.
I also had to choose between mouse lag caused by V-Sync (the other .ini tweaks only making a tiny bit of difference) and the strange physics noises inside buildings caused by turning off V-Sync.
That is until someone posted some advice in a thread, this isn't my advice I owe it to them, but it has fixed the issue for me, I can now disable V-Sync and play without any physics bugs. I need more time to confirm this fully, having a playtime of only 4 hours though. But, so far so good.
1. Disable V-Sync in your .ini file
2. Download a program called dxtory from http://dxtory.com/
3. Install it (Microsoft Network Framework 4 required)
4. Start it, go to the advanced tab (it looks like a green computer chip) and tick the FPS limit box, type in your desired limit. I chose 59 FPS, one lower than my screens refresh rate. I have heard 80 FPS recommended elsewhere too.
5. Without closing dxtory, start Skyrim.
6. Enjoy mouse lag free, physics bug free gameplay.
7. After exiting Skyrim, also close dxtory or your FPS limit will remain in-place for other programs too.
