Comment 0 for bug 1766048

I did a full update of my system which has been running 18.04 since the beta 2 update and I've noticed now that the desktop feels quite sluggish. The last update I did was about 5 days ago. I'm not sure which package was the culprit as several were updated (30+).

However - I think it has something to do with Gnome. I have a 75 Hz monitor, and it seems like Gnome animations, as well as just actions like moving windows around, feel like they're rendering at a lower frame rate. There is a lot of jitter too almost like tearing.

Moving the mouse cursor around feels like 75 Hz though (super smooth), as well as when I play games. Had no issues prior to running 'apt upgrade'. And I can confirm my monitor is running @ 75 Hz.

I'm running the stock Ubuntu kernel currently but I did try installing the most recent stable kernel (4.16.2) and that exhibited the same issue. One thing I did notice, is that setting the flag amdgpu.dc=0 in my Grub config did fix the tearing and general lag issues with moving windows around. However, it isn't a complex fix as that instead introduced stuttering with the mouse cursor.

With a fresh Beta 2 installed (no package updates) this tearing/lag issue is not present.

System specs:

Threadripper 1950X
64 GB RAM
Radeon Pro WX7100
LG 38UC99 monitor (3840x1600 res).

Description: Ubuntu Bionic Beaver (development branch)
Release: 18.04