» Thu May 31, 2012 11:16 pm
I'm pretty sure the reason everyone experience mouse lag is because their FPS is at 60. This is often in dungeons and when looking up at the sky or down at the ground, because then there are little stuff to render.
Most people say "disble V-sync to fix this" (setting iPresentInterval=0 means that you disable V-sync), which is wrong. That's a bad idea, because it has been shown that disabling V-sync (iPresentInterval) can cause crazy physics behaviour, issues with the in-game time, sound issues that so sounds never stop, flickering water, etc. In other words it's a bad idea to disable V-sync.
The solution is to cap your FPS in Skyrim using an FPS-capper/limiter. NVIDIA Inspector (google it and download it, it's free, safe, and very good) has one if you have an NVIDIA card. Dxtory is also a program you can use if you have an AMD card to cap the FPS (also read the relevant section 2.1 in this thread if using Dxtory: http://www.gamesas.com/topic/1329260-b1gbaddaddys-big-post-of-fixes-and-tweaks/).
You need to cap your FPS in Skyrim to 57-59, in other words below 60. The reason you experience lag at 60 FPS is because of a bug in Bethesda's engine called "64 hz bug". Basically, it means that your computer screen renders at 64 hz, but Skyrim only renders at 60 hz. That means 4 frames per second are being skipped, which results in lagginess or mouse lag.
I also recommend having a decent mouse. I switched to a temporary, cheap and crappy mouse when my old one broke. It caused me to experience quite a lot mouse lag, even though I had my FPS capped at 58.