I'm running Ubuntu 16.04 with the latest updates on a 2009 Dell T5500 workstation with an nvidia Quadro NVS card. When I run the noveau drivers, I get errors and lockups, so I run the nvidia 340 drivers (which are the recommended ones). I've tried a few other versions of the drivers, and still get the same issues.

The problem that I have is that on boot, the Unity menu and alt-tab switchers work quickly, but after I've left the X session up for a while, they start popping up at about 1 FPS over the the course of 5-10 seconds. Switching to the MATE interface "fixes" the issue, but I like the easy "search for applications" launcher that Unity provides.

The dash "include online search results" is off, but I think that was a red herring, given that the alt-tab switcher exhibits the same behavior. I've tried toying with CompizConfig settings (e.g. Dash Blur, disabling animations, etc), to no avail.

I just did a fresh install of 16.04 yesterday on a brand new, recent SSD, and I'm getting the same issues today, and I'd seen the same issue going back at least to 14.04.

So, two possible answers I'm looking for:

  1. How can I fix this to make the menus and switcher pop up quickly? or
  2. Does there exist another launcher for an alternate UI (e.g. MATE) that does the indexed search app launcher?

Note that running

unity --replace 


compiz --replace

does not alleviate the problem for more than a couple of minutes.

I've installed the CompizConfig Settings Manager and tried disabling anything that seemed relevant: Animations, Fading Windows, Window Decoration, Dash Blur, etc. Even if I choose Enable Low Graphics Mode, the affected windows don't pop up instantly. I've even gone into the Ubuntu Unity Plugin and set all of the Menus durations to 0, to no avail.

When running htop -d 1 (i.e. to get quick updates on the CPU usage in tenths of a second), I see a brief spike in CPU utilization from compiz and /usr/lib/xorg/Xorg during the issue, and compiz stays pegged using a full CPU until the problematic window goes away. (CPU is 4 core hyperthreaded Xeon)

  • Could it be a RAM shortage? How much memory does your machine have and how full is it when you experience the lags? – Byte Commander Sep 20 '16 at 16:08
  • The machine has 24 GB of RAM and that doesn't seem to be the issue: > $ cat /proc/meminfo > MemTotal: 24682392 kB > MemFree: 387300 kB > MemAvailable: 21106440 kB > Buffers: 265572 kB > Cached: 20613328 kB – Aphoid Sep 20 '16 at 20:43

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