Windows 8.1 upgrade has a mouse bug which creates problems for the gamers. Windows is working on the fix, but the date is still not known.
Microsoft acknowledged the problem and is actively working on figuring out what caused the problem and fixing it. They are getting a lot of feedback from the gaming community. It appears that, what is known as a mouse lag, is in fact more than one issue, depending on the game played and input methods. While Microsoft is working on a patch, it did not release the date when the gamers can expect it.
There are several workarounds that some gamers found helpful: for example, if you the mouse cannot reach all areas of a game, Microsoft suggests disabling DPI scaling. It can be done with the right-click of the game's icon, Properties, Compatibility tab, and then checking the box next to Disable display scaling.
Source: Hot Hardware