Windows 8.1 Mouse Lag Patch
If you have been having trouble with mouse lag in Windows 8.1, Microsoft have released a patch to fix it. Downside, any game not on the supported games list on the patch page will need you to mess around in the registry to fix it. Thanks Microsoft. :(
Mouse pointer stutters or freezes when you play certain games in Windows 8.1 and Windows Server 2012 R2
This should be most noticeable for WoW players as Blizzard have posted the patch as a fix for the jumping camera bug. Unfortunately it isn't on the supported games list so off spelunking in the registry you go!