Kubuntu 16.04 newly upgraded from 14.04 freezes after every operation

[cdupree]

After practically every operation that requires computing my system, newly upgraded to 16.04 from 14.04 this afternoon, freezes for a minute or so. I bring up a new tab in a browser, and a minute or two later I can type into the address bar. I clink on a link and a new tab pops up, then sits there for a minute or two. I switch windows with a shortcut key sequence and it freezes. I can type into this box as long as I want, but if I need to check something in a different window I'll have a freeze each time I switch.

During these freezes the mouse cursor moves but can't click anything and I can't type. I can mouse over the system menu bar without it raising to visibility, though when it finally unfreezes the actions I took while it was frozen have their momentary effects.

One poster on another site suggested I had no swap space, but sudo swapon --show says there's 8GB of swap, though none used.

My system is now so slow as to be unusable for anything but emergency operations, so I'll be super grateful if anyone can suggest something I might try, check, or modify.

- ced

[GreyGeek]

What does ksyslog show right after one of these freezes?

Or, open ksysguard, set it so that it is always on top and sort of the CPU so the most used process is at the top (resize it to a corner out of the way with just the first few lines showing), and then play with FF again and watch what happens in ksysguard.

[cdupree]

Okay, this is one of the strangest experiences I've had with software (and I started at DEC in '78). After multiple reboots and attempts at finding configuration issues to work on last night, I left the system running and freezing nearly constantly. When I got up this morning the freezes had stopped; I don't think I've experienced a single one today. Now what I have is lots of display anomalies, e.g. the screen doesn't repaint when a window is minimized or I change desktops, task bar icons flicker around the edges as I hover over them.

Every time I update to a new version of Kubuntu I have problems like this, which is why I put off updating for so long that I was coming from 14.04. Is that possibly related to my current issues? Is it a graphics driver, or where should I look for clues?

[GreyGeek]

I suspect that akonadi doing it preliminary indexing after a fresh install or large upgrade may be the problem. You can turn the indexing off for the day and turn it on at night while you are sleeping.

For your other symptoms you may want to try a different rendering backend, scale method and vsync method.

[cdupree]

Ah, that makes sense. I don't know how to change rendering backends, scale methods, or vsync methods, though.

[vinnywright]

Every time I update to a new version of Kubuntu I have problems like this, which is why I put off updating for so long that I was coming from 14.04. Is that possibly related to my current issues? Is it a graphics driver, or where should I look for clues?

it is likely the problem ,,,,I do not think it is even recommended to try an "upgrade" from 14.04 to 16.04 their are big differences in the 2 ...did you have a separate /home partition that you are "reusing" ,,,,,if so their will be config files that do not work with the new ver of plasma .

VINNY

[cdupree]

I did not have a separate /home partition so perhaps I avoided that. I just switched to XRender and that seems to have fixed my display anomalies. Now things seem to be in pretty good shape, so many thanks for the help, GreyGeek (once again!) and VinnyWright!

[GreyGeek]

Ah, that makes sense. I don't know how to change rendering backends, scale methods, or vsync methods, though.

From the menu choose System Settings --> Display and Monitor --> Compositor