KDE slows down after some idling

[wconstantine]

I'm running KDE on Ubuntu 12.10 from the original repos. KDE slows down significtantly after a few hours of idling. I have a very powerful computer. 16 GB RAM, i5 processor, GTX 660 graphics card and an Intel SSD. Driver used is the on in the latest nvidia-current package. I have no idea what the problem can be. After I've used the system for some time after it has become slow from the idling, it starts getting faster and more snappier again. Anyone know what this can be?

$ free -m
total used free shared buffers cached
Mem: 16032 6129 9902 0 162 4012
-/+ buffers/cache: 1954 14077
Swap: 16367 0 16367

$ uptime
20:17:54 up 1:53, 2 users, load average: 0.50, 0.63, 0.52

$ sar -u 2 5
Linux 3.5.0-27-generic (fimbulwinter) 04/15/2013 _x86_64_ (4 CPU)

08:19:51 PM CPU %user %nice %system %iowait %steal %idle
08:19:53 PM all 4.63 0.00 0.63 0.00 0.00 94.74
08:19:55 PM all 3.40 0.00 0.50 0.00 0.00 96.09
08:19:57 PM all 4.11 0.00 0.87 0.00 0.00 95.01
08:19:59 PM all 4.47 0.00 0.99 0.00 0.00 94.53
08:20:01 PM all 4.03 0.00 0.50 0.00 0.00 95.47
Average: all 4.13 0.00 0.70 0.00 0.00 95.17

[oldos2er]

Is it slowing from hard drive access? You can use top or htop to see which processes are consuming CPU cycles.

Do you have Nepomuk file indexing running? If so, try turning it off and see if it's better.

[wconstantine]

Is it slowing from hard drive access? You can use top or htop to see which processes are consuming CPU cycles.

Do you have Nepomuk file indexing running? If so, try turning it off and see if it's better.

iowait % from the sar output would be high if it were hard drive access I think. Also, the CPU usage is constantly low, so it's not really necessary to check which process is utilizing CPU. I will try turning off file indexing since I'm not using it. Thanks anyway.

[dabl]

It may be the scheduler (cfq is default) or the cpufreq control in the kernel, or both, or interactions between them. You could try deadline or noop and see if it makes any difference. In your BIOS you may have the option not to let the OS control the CPU speed -- if so you might want to try it that way. My Asus board has that.

The consequence of forcing it to run at its highest speed, of course, will be more energy consumption including when it is running and you aren't using it.