Plasma-desktop becoming very slow

[Duncan]

Stephan Diestelhorst posted on Fri, 08 Jun 2012 09:25:23 +0200 as
excerpted:

>   after leaving my system running for a while with virtuoso-t eating
> some CPU, virtuoso-t eventually finishes and everything is fine.
> 
> However, although the CPU load stays very low, plasma-desktop is *very*
> slow.  Clicking on the virtual desktops in the bar will switch the
> desktop after sevaral minutes(!), and the list of windows is not really
> updated.  Also, Alt + F2 takes approx. 45 secs to open the krunner
> dialog.
> 
> Switching desktops with Ctrl + F1 is fast and the respective
> applications work fine, too.
> 
> This is on Kubuntu 11.10 with KDE 4.8.2.
> 
> Any ideas how to fix this?

How I fixed the general problem honestly isn't going to be easy for 
people running most binary distros, tho you can try part of it and see if 
only that part works.

I run gentoo, which is a scripted build-from-sources distro that 
emphasizes giving the local system admin the choice to turn build-time 
optional features on or off as desired, via what they call USE flags.  
Here, I turned the semantic-desktop USE flag off, rebuilt the various 
parts of kde depending on it (and switched to something else for anything 
kdepim related as that all depends on akonadi, which in turn depends on 
semantic-desktop, so kmail replaced with claws-mail, etc), and uninstalled 
all the semantic-desktop related components, including nepomuk, virtuoso, 
redland, rasqal, etc.

KDE was *MUCH* faster and more responsive after that, here, and a couple 
other folks have tried it too, and found kde faster for them too, tho at 
least the one said it wasn't as dramatically so for him as it was for me.

The half-way alternative that you can try without having to do your own 
builds is simply turning off as much of semantic-desktop as you can.  
Here, that helped some, but not as much as building entirely without it 
and uninstalling the various no longer needed components.

Since I did this back with early 4.7, I don't know how much of the 
controls have changed since then, but in kde system settings there should 
be an option to either simply disable indexing (or tell strigi to not 
index certain directories while leaving it on, YMMV), or to turn off 
nepomuk entirely.  Do note that if you run kmail or anything else using 
akonadi, turning off nepomuk turns off some functionality there, too.

As I said, for me, turning that off helped some, but not as much as 
building entirely without it, which isn't an easy option for binary-distro 
folks.  But you can try it and see if it helps.

As for krunner, you can click the wrench icon there, and turn off various 
of its addons.  Look for options like searching in mail, etc, that are 
semantic-desktop related.  It's likely that one of them is eating the 
krunner cycles, and turning it off, once you find the option doing it, 
should speed up krunner dramatically, entirely separate from turning of 
nepomuk, etc, above.  (There was a bug in one of those krunner addons 
some kde versions ago and turning off one of the krunner addons was a 
suggested workaround, but that was 4.6 era and I don't recall which one 
it was, except that searching in mail seems to ring a bell so that might 
be it.  I turned off several I didn't need, including that one, and it 
/was/ faster, so it was a good suggestion for me. =:^)

-- 
Duncan - List replies preferred.   No HTML msgs.
"Every nonfree program has a lord, a master --
and if you use the program, he is your master."  Richard Stallman

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