Jon P. Inghram

Ah yes, the classic "It's too complex to us to fix" resolution, nevermind that a simple mod that's only 22 lines long fixes it.

Can confirm on 1.18 pre2.

With an older i7-860 it's taking about 55 seconds from launch to CPU usage returning to normal, and around 400 seconds of CPU time.

Argh, I did search before posting but apparently didn't use the correct terms as this is clearly a duplicate of MC-239041

I took the relevant files from the LWJGL 2.9.3 nightly build from today and stuck 'em in a zip file with the correct directories and .sha files so the launcher doesn't automatically download the old 2.9.1 files:

https://drive.google.com/file/d/0BzS6i2JCDwdtVEYxd0FxR2lIbkU/view?usp=sharing

Extract the folders in the archive into the \.minecraft\libraries\org\lwjgl\lwjgl folder and it'll overwrite the LWJGL 2.9.1 files.

If you want to do it yourself, you can download the 2.9.3 nightly build yourself http://legacy.lwjgl.org/download.php , replace Minecraft's LWJGL 2.9.1 files and make new .sha files to match the new versions so they don't get overwritten by the launcher.

Ah, that DID fix it! 😃

I had to download 2.9.2 and insert that version first to get the one you linked to work correctly, and now the mouse works perfectly, thanks! Hopefully Mojang will update to 2.9.3 when it's released then. Again, many thanks!

Unfortunately Minecraft doesn't run correctly if I try that .jar. It starts in a tall, narrow window that is always pushed most of the way below the screen: http://i.imgur.com/sIpQVgQ.jpg . If you enlarge the window it's mostly blank with the normal animated background in one corner, and no UI or any other way to interact. They're still using LWJGL 2.9.1 in minecraft, perhaps it'll work correctly if they update the included version.

I found a report of a similar problem in SDL ( https://forums.libsdl.org/viewtopic.php?t=3463&sid=964c840d9a6461f79e00ccd745da6c1c ) which used/uses the same WM_MOUSEMOVE messages from Windows to track mouse movement as LWJGL.

I just checked and this does not happen when running Minecraft in Linux (Ubuntu 14.04) on the same system.

Here's a better video of this problem: http://youtu.be/985aI-JfXUE

The frame rate is locked to 30 fps, and I just move the mouse in small circles. The mouse look sensitivity smoothly drops and then jumps back up in a repeating cycle as long as any key is held down. As soon as the key is released the movement returns to normal.

You might try rebinding the crouch function in Minecraft to a mouse button to see if it's a keyboard input problem. You could also try playing with the Windows character repeat settings in the control panel keyboard properties. Try setting the repeat delay to the longest and the repeat rate to the slowest (taking note of what they default to so you can set it back to what you're used to, there's no "default" button to reset them.)

Fisheye projections cause lines to be curved, which isn't what is going on here here. The unpleasant distortion seen with wider fields of view is a natural effect of a perfect rectilinear projection which can be seen in my attached screen shot with the two inset enlargements of trees, one from near the middle of the screen and the other from the edge.

I've since updated my video drivers to 334.89 and also tried the Java 1.8 early access release without any changes. I suspect the issue is in the way Minecraft and/or LWJGL handles repeating key input from keys being held down.

Just discovered something: It's directly influenced by the Windows keyboard repeat rate setting. If I set that to the minimum the effect is much less obvious, and when at max it becomes even more visible.

Yes, when I first noticed it happening I was using the 332.21 drivers. I have since updated to the beta 334.67 drivers, http://www.geforce.com/drivers/results/72576 , with no change. I have tried booting with no other USB devices besides the mouse. I have tried connecting the keyboard (a Microsoft Natural Keyboard Elite) with both via PS/2 and USB without any effect. It happens with both Logitech G500 and a Microsoft Wheel Mouse Optical mice. This will also happen if I bind a mouse button to perform a keypress instead of a regular mouse button press.

Pressing multiple keys simultaneously effects the issue. If you start by, for example, holding shift, and then press and release the "G" key, the mouse look movement returns to normal even though you're still holding shift to crouch (and you do remain crouching.)

This effect is still present, but almost imperceptible on my laptop running Windows 8.1 64 bit with an Intel Core i5-3230M and integrated HD 4000 graphics.

I found a couple forum posts of other people with the same issue, apparently it's been around for a little while:

http://www.minecraftforum.net/topic/1302194-intermittent-mouse-sensitivity-loss-ingame/
http://www.minecraftforum.net/topic/1872298-mouse-movement-diagonal-player-movement/

And I just found another bug report that might be related: https://bugs.mojang.com/browse/MC-43093