How do I reduce mouse sensitivity in Minecraft?

Whenever I set my priority to high or above normal my mouse goes crazy. Every time I want to turn to the right or left a little bit with the mouse, it makes me do a 360. And when I try to engage in pvp, I always die because when they get behind me I spin in circles trying to simply face them.

This is really making me tired of Minecraft and I need a solution, fast! I haven't really tried finding a solution because none worked. I know its not my mouse because I tried the mouse on my friend's computer and it worked just fine.

This may not be to do with your sensitivity. I run Minecraft on a low-spec machine and also have this issue when I change priorities.

The issue here is that when you increase the priority of Java, you're making it higher priority than your mouse drivers. This means that when Minecraft is taking a large amount of processing power, the part of your computer which tracks your mouse is forced to wait- causing you to lose mouse control.

The obvious solution here is to not mess around with the priority settings and set Minecraft back to normal. If you have framerate issues, there are other solutions- I recommend Optifine. I recommend this, since screwing around with priorities can often have odd or unforeseen effects.

An alternative would be to find the process(es) related to your mouse drivers and ensure they are at equal or greater priority to Java's. This should stop the mouse issue.

Unfortunately, I am completely unable to reproduce any potential issues caused by changing the priority of the javaw.exe process (which is the process controlling Minecraft).

However, there is a sensitivity slider in the options menu:

You can set your sensitivity anywhere from "*yawn*" to "HYPERSPEED!!!!" It is possible that your sensitivity setting was bumped up, which would cause the effect described.