I had Ubuntu 16 then upgraded to 18 then installed KDE. Now I have slow main menu appearance. It takes 1-2 second and unrelated with animation.
I saw suggestions to remove
xorg.conf, but didn't find one.
All other popups are also enslowed.
You mention that you started with Ubuntu 16 and upgraded to Ubuntu 18; from the tag I infer you mean 18.04 (BionicBeaver) from either 16.04 or 16.10. Have you read the release notes or change summary for Ubuntu / Kubuntu 18.04? Many of them are relevant to blacklisting drivers for particular hardware, including graphics.
if the files in
are from Ubuntu 16.04 but the kernel and drivers are for Ubuntu 18.04,
this could potentially cause a performance issue,
although I don't know enough about your hardware to look for any known bugs.
On my machine,
provides workarounds for
Deciding which configuration files to keep the same and which to upgrade to a newer version can be a delicate process, so some folks just prefer to re-install from scratch to ensure they are using the recommended configuration from their distribution. This is the method that I personally find to be the most expedient; I re-install onto a new disk and then copy my data over. After that, I mainly migrate configuration for my home directory and leave global configuration largely the same, except for things like wifi connections and printers.
This brings up the consideration of configuration files in your home directory,
The package manager generally leaves these files alone, so to isolate the bug
you may have to start with the default Plasma 5 configuration
and bring in your customizations piece by piece.
(You can also use a binary search strategy,
adding half your configuration settings at a time
and backing up if the half you added re-introduces the bug.)
For example, the configuration for many plasma applets is stored here:
How an older configuration file will affect performance depends on a variety of factors, such as which application launcher you are using. For example, are you using Application Menu (kicker), Application Dashboard (kickerdash, the full screen launcher), or Application Launcher (kickoff)? You can switch between them with right-click → "Alternatives...". Are they all equally enslowed? Does this change if you alter the settings?
You can try toggling settings like
("Expand search to bookmarks, files and emails").
You can change this via right-click →
"Application Menu Settings..." or "Application Launcher Settings...".
Here's what it looks like for Application Launcher (kickoff):
By the way, how do you actually know it is unrelated to animation?
Have you tried disabling animations?
Have you tried disabling compositing?
Have you recorded a screencast demonstrating the problem with e.g. gtk-recordmydesktop?
It would be helpful to have a screenshot of your "About System" screen, like this:
This would provide information about the exact version you are using (useful for other folks who read this question) and some basic hardware information.
I also use KDE on Ubuntu 18.04, but I don't experience anything like what you're describing. Without more information, I can only speculate as to the cause of the delays you are experiencing.
If you want to dig deeper,
the source code for the
is in the
For example, here is the code to generate the action list for
and here's the QML code for part of