Ubuntu – Mouse cursor lag after lock screen, 64 bit 12.04

12.04lock-screenmouse

Recently I have noticed that when I return to my computer after it has been "locked" for a while, the mouse pointer has significant lag. The cursor position appears to only update a few times a second. Moving the mouse results in the pointer "following" the movement in a jerky kind of way, and then continuing for some fraction of a second after I have stopped using the mouse.

Replacing the mouse has no effect. (I have two differently branded and constructed usb optical mice). Plugging either mouse into a different usb port has no effect.

Once the problem was resolved by "suspending" the system, and then re-starting it with the power switch, but this does not work every time. So far, the only fool-proof fix is to shut the system down and re-start it (re-boot).

I have tried this suggested fix. It had no effect.

Best Answer

After months of this recurring problem, I believe I have finally found the cause:

Intel Sandy Bridge GPU power management - when i915 rc6 is enabled, I get occasional USB slowdowns after resuming from a lock screen. With it disabled, the symptoms are gone for good.

Here's precisely what I did: Edited the file /etc/default/grub to include the line

GRUB_CMDLINE_LINUX="i915.i915_enable_rc6=0"