Sluggish performance when using Compiz (Unity, GNOME Classic)

Bug #1005152 reported by Newfie on 2012-05-27
This bug affects 3 people
Affects Status Importance Assigned to Milestone
Compiz Core
compiz (Ubuntu)

Bug Description

I've reported similar issues to this in the past, and mostly they have been fixed. However, over a month after 12.04's release, I'm still facing some hiccups related to overall performance.

When Compiz is running there seems to be a very slight delay when using the mouse or keyboard. It's minor enough that I did not notice it until I started using another DE for a while. But now that I see it, it's quite noticeable.


- Keyboard input delay: Seems to be an extremely brief delay after pressing a key, giving the illusion of using a physically sticky keyboard. I type quite fast, so I can often see the characters "trailing" behind my keystrokes. This can be demonstrated by opening a text editor and holding down any character and letting go after a few seconds; the characters briefly continue to show up on the screen after the key is no longer pressed.

- Window "follows" the cursor when using swift dragging.

- Highlighting follows the cursor in a very noticeable way.

- Brief delay when clicking or using scroll wheel.

Expected result:

Performance should be identical to that of Unity 2d or GNOME fallback (without effects). After using Unity 2d for a while, these delays are extremely noticeable to me since switching back to Unity.


Originally I thought this was an issue with Fglrx. However, I tried it out on other hardware and drivers with similar results. Unity 2d is extremely responsive and quick, whereas Unity or GNOME Classic with effects feels slightly sluggish. I also have features from amdccc disabled (tear free, etc) which would normally cause lag.

ProblemType: Bug
DistroRelease: Ubuntu 12.04
Package: compiz 1:
ProcVersionSignature: Ubuntu 3.2.0-24.39-generic 3.2.16
Uname: Linux 3.2.0-24-generic x86_64
NonfreeKernelModules: fglrx
ApportVersion: 2.0.1-0ubuntu7
Architecture: amd64
CompizPlugins: [core,composite,opengl,decor,grid,regex,place,mousepoll,vpswitch,move,compiztoolbox,imgpng,resize,session,gnomecompat,animation,wall,unitymtgrabhandles,expo,workarounds,ezoom,fade,scale,unityshell]
Date: Sun May 27 09:34:23 2012
DistroCodename: precise
DistroVariant: ubuntu
InstallationMedia: Ubuntu 12.04 LTS "Precise Pangolin" - Release amd64 (20120425)
PackageArchitecture: all
 PATH=(custom, no user)
SourcePackage: compiz
UpgradeStatus: No upgrade log present (probably fresh install)

Newfie (mn-newfie) wrote :
tags: added: compiz-0.9
Daniel van Vugt (vanvugt) wrote :

Newfie, thanks for the detailed report.

I can't reproduce any such lag yet. But I have more (slower) hardware I have yet to test...

Do you have ccsm > Workarounds > "Force full screen redraws (buffer swap) on repaint" enabled? Please try with and without that option. There are reasons why that option might give you more, or might give you less lag. It might give you more because it allows compiz to pipeline rendering of multiple frames before they're actually displayed, hence a couple of frames lag. It might give you less lag for the same reason though -- because more of the work is offloaded from the CPU to the GPU and the CPU can better keep up.

Newfie (mn-newfie) wrote :

I just gave that option a try. Immediately there were *some* improvements, but not entirely smooth. Text selection doesn't trail behind as much, and scrolling is a slight bit less jittery. The keyboard input is still slightly delayed.

I'm going to keep this enabled for a while and see how it works.

Also, I'm confident that hardware is not an issue for me. I have a Phenom II x6 CPU, 8 GB of memory, and a low end (but recent) dedicated AMD GPU. Definitely more than enough to run Compiz. Without fglrx it is a little better, but still not quite right. That rules out the blob being the issue.

The other PC which I have tested is fairly low-end, but experiences no typing delay- only scrolling, window drag lag, etc. It has an Intel CPU and NVIDIA gpu.

Launchpad Janitor (janitor) wrote :

Status changed to 'Confirmed' because the bug affects multiple users.

Changed in compiz (Ubuntu):
status: New → Confirmed
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