Why does Dolphin take forever to load on Kubuntu 20.04 all of a sudden?

I am using Ubuntu 20.04 with kde plasma. All of a sudden, my Dolphin file browser takes forever to open. Earlier it opened instantly, but now it is taking almost 30 seconds to start.

This seems to have started after an update; when I use kernel 5.11.0-38-generic there is no issue: the problem occurs when I use kernel 5.11.0-41-generic. In addition when on 5.41 the whole system seems to run slower.

When I run dolphin from the command line, there is no error output, and it is as slow as before to open.

I am using an Intel 4690k CPU with 16GB ram and SSD. I checked my drive health and it is fine.

The kernel versions you are quoting are very strange. Please add in the question the output of

$ uname -a
$ lsb_release -a

in both cases. Now, a few things to try:

1. pkill gvfsd-trash is proposed here as a solution. If that works, we may try further understanding. Further diagnostics shown here.
2. systemctl mask upower.service is proposed here as a solution. If that works, we may try further understanding.
3. Check with top and strace -c dolphin (and exiting dolphin) if that can give a hint of the cause for the lag. (related)
4. What do you get if you run dolphin from the command line? Please post in the question. (related)
5. baloo, loaded with dolphin, is often a problem, but it shouldn't be different among kernels. Could you confirm?

Related:

1. https://forum.kde.org/viewtopic.php?f=224&t=160306