Dolphin and other KDE applications suddenly start to slow down

Tiertier · September 25, 2023, 7:48am

Hello everyone,

I’m looking for some help to solve or identify a problem with KDE.

I currently use the latest LTS version of Ubuntu 22.04 with KDE :

plasma-desktop : 4:5.24.7-0ubuntu0.1
konsole, dolphin, gwenview, kate : 4:21.12.3-0ubuntu1

I only use the machine from remote sessions via the VNC.
tigervnc-standalone-server : 1.12.0+dfsg-4

When I start a new VNC session with a KDE environment, everything works properly.

After a time of use that can vary from a few minutes to several days, Dolphin suddenly slows down. It will then take more than 15 to 20 seconds to open it. Navigating within directories becomes extremely slow (10-15 seconds between the click and the reaction). The scroll also becomes very slow.

If I open a second VNC session, this slowness also affects my new screen. But other users on the computer don’t have this problem at the same time. Although this can happen to them also but not at the same time. Dolphin can therefore be very slow for only a user.

The only solution is to kill all the processes that belong to the user and to relaunch a new session, and there the problem disappears.

When I detect a big slowdown of Dolphin, other KDE applications such as Gwenview and Kate also become extremely slow. On the other hand, the starting menu of KDE is still operational, and doesn’t seems to be impacted.

I’ve been using KDE for a while on a laptop and I’ve never met this kind of problem. The only difference here is that this machine mounts NFS shares via autofs.
But this does not seem to be the real source of the problem because it is quite possible to continue to use and browse NFS shares without any issues with other applications such as Konsole, Libreoffice, …

I can’t find anything that can help me in system log files, or in session logs or VNC server. No
error to be noted when I launch dolphin from a command line.

Do you have ideas to solve or at least identify the source of the problem to make a bug report?

Thank you in advance for your help.

CharlesRKiss · December 24, 2024, 3:23am

Hi, I’m having the same problem with Gwenview. Did anyone figure this out?

In my case, I think it might be Gwenview checking and rechecking a “bad” USB port. This is generally where it stalls for a few seconds according to strace, and this will happen a few times:

0000:54:00.0/usb4/subsystem", “…/…/…/…/…/…/…/…/…/bus/u”…, 4096) = 34
openat(AT_FDCWD, “/sys/devices/pci0000:00/0000:00:02.1/0000:45:00.0/0000:46:08.0/0000:4c:00.0/0000:4d:0c.0/0000:54:00.0/usb4/uevent”, O_RDONLY|O_NOCTTY|O_CLOEXEC) = 32
newfstatat(32, “”, {st_mode=S_IFREG|0644, st_size=4096, …}, AT_EMPTY_PATH) = 0
read(32,

I get usb4 warnings during bootup, dmesg:

[376287.141095] usb usb4-port4: Cannot enable. Maybe the USB cable is bad?

johnandmegh · December 25, 2024, 6:38pm

Hi! That’s likely to be a bit of a different triggering issue, so it may be worth creating your own topic just to make sure you have a title that best captures what you’re looking for help with.

In general, I would say I’ve noticed on my personal systems, across different OSes and installations, that USB devices or ports that are physically failing tend to throw off a lot of other system behaviors.

In my case, the only real solution ended up being to either totally disable, or unplug/replace, the faulty component - there could be other solutions, just sharing my own experience there.

CharlesRKiss · December 28, 2024, 2:01am

Thank you, I appreciate this.

There are no components plugged into the USB port, but I had allocated a port to a hard drive, according to the motherboard instructions (Taichi), and I was left with an unusable USB input, out of like 6 or 8, if I recall. But I didn’t think it would lead to any problems.

I might go over to the Taichi message board, after I take a closer look at the machine and its manual. Perhaps I will reconfigure the USB stuff.

Perhaps you put me on the right track.

CharlesRKiss · December 31, 2024, 1:37am

Dang. Lo’ and behold, Johnandmegh.

There is a small “Smart Zero Fan” switch on the Thermaltake power supply, which I had off because, being paranoid, I wanted the fan to run 24/7.

The switch appears to be part of a large module that controls several fans, which is plugged into one of the USB 2.0 headers on the motherboard.

I turned the switch on, and suddenly Gwenview pops right up.

AND, I no longer find the usb4 “cable is bad” error in dmesg.

AND, I am seeing evidence that this is solving a problem with rotated thumbnails is Dolphin, believe it or not.

I will spend the next few days keeping an eye on this to confirm!

johnandmegh · December 31, 2024, 6:36pm

Glad that seems to have helped! Getting flashbacks to the Turbo button on old PCs

CharlesRKiss · January 2, 2025, 11:56pm

Okay, it helped a lot, but it was not the switch after all.

I had a 100 ft powered USB cable that was not powered on.

After unplugging several USB devices, while fluctuating the “Smart Fan” switch between on and off, and rebooting, I came to the conclusion this issue has nothing to do with the fan switch, and everything to do with a unpowered USB cable.

My apologies to Thermaltake!

The gist is this: Improper USB connections will definitely slow down Gwenview and Dolphin application launches — severely.

I consider this matter closed.

Thank you so much, johnandmegh!