OS: Lubuntu 12.04 64-bit (Ubuntu 12.04 with LXDE)
System: HP DV7-1040ED notebook with Nvidia GPU: NVIDIA Corporation G96 [GeForce 9600M GT] (rev a1)

When working with certain applications windows become unresponsive or take ages to load and when I move my mouse outside of the window the application immediately becomes responsive again. Some examples:

  • Thunderbird: opening Thunderbird goes fine but as soon as I click on a folder Thunderbird starts loading which takes way too long. If I just let Thunderbird continue it will eventually become responsive again. If I click on a folder and immediately move my mouse pointer outside the Thunderbird application window Thunderbird immediately loads the folder and remains responsive.
  • Qtractor: if I load a project with a lot of plug-ins it takes up to 40 seconds for Qtractor to load the project and become responsive. If I load the same project and move my mouse pointer outside of the Qtractor window that same project loads within 10 seconds.

If necessary I could upload a screencast since this is quite a generic and vague issue. I've tried different window managers but that doesn't make any difference. On the same notebook I also have a Ubuntu 12.04 32-bit with Unity which doesn't show this behavior. My 64-bit Lubuntu machine at work seems to be unaffected also. Regarding Qtractor loading that specific project, I've run a strace on Qtractor and it seems as if it's looping on loading the different DSSI plug-ins (ZynAddSubFX DSSI in this case). I'm running a non-debug build unfortunately and will install a debug build and post any useful outcome here. This issue only occurs when I start qtractor /path/to/project from a terminal or from a desktop file. When I start Qtractor as is and then open the project from the menu it loads fine.

I hope someone's got a hunch of what's going on here and if any additional information is needed I'm happy to provide it.



1 Answer 1


Found the culprit, it's the nouveau driver. After installing the proprietary nvidia driver I don't have any lagging windows anymore. So there is a workaround for this issue. I would prefer using the open source nouveau driver though so I'm going to try and figure out why nouveau is causing these unresponsive windows. Since I've found the cause of my issues I consider this question answered.

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