Hi!

I am being annoyed by one performance problem in Plasma for some time already. Seems it has appeared with one of backports updates.
The problem is basically parts of applications freezing for a moment after some kind of action being performed either by the app or by the user. First I have noticed it in Spotify and I thought it would be their bug again. After song ends and is changed to another one, the app won't react to many of actions from user. Sometimes you just cannot stop the song, change it, progress bar and cover art don't refresh... Sometimes whole application acts frozen and you need to wait to be able to do anything.
But then I started noticing it in many other places as well. I will try to remember a few of them:
- system prompts asking if to delete, replace a file
- trying to access settings in Telegram messenger
- pretty randomly in Konsole
(I might update this list once I remember about something else)

Worth to mention this issue appears every single time in Spotify, but most of other issues you need to pass once after booting system at some point and then this feature will work just fine.
And one more note worthy detail: these lags seem to last for the same or at least comparable amount of time. Looking at Spotify player, the count starts showing something else than 0:00 when the song is on 0:23. Haven't ever been trying to check out if the lag lasts for exact same amount of time, but it seems really comparable.

Do you know what this issue could actually be about?

EDIT:
Including some system info
Plasma 5.10.3
Kubuntu 17.04
x86_64 Linux 4.10.0-28-generic
Intel Core2 Quad CPU Q8300 @ 2.499GHz
Nvidia GeForce GTX 670
8GB RAM

Also I am wondering if to consider one more issue, which have appeared together with the main lag issue. Looks literally like this bug from Windows XP, but in micro scale https://c2.staticflickr.com/4/3474/3751 ... b328_b.jpg It appears for much less than a second when hovering over another window. Only over other windows and seems to be worse over heavier windows.