14.2 Dolphin file copy progress notifications
 

In copying files between drives (mostly disc to USB as things are getting organized) it is noted that the progress notification for Dolphin does not always show the copy rate. Frequently it just shows 0b copy rate, even though the system is busy copying things.

Any ideas on how I should search out this different notification behavior?

I just installed 14.2 within the last week, so I am suspicious that something may not be perfectly right.

Seen this often, don't think it's just kde. Probably udisks or the kernel.
Sometimes it will report extreme rates and note it finished the write, but the drive LED will still blink for few minutes after that.
In this case the progress dialog gets stuck at '100% /0 kb/s' and does not close until the drive stops writing.
Try replicate the same problem in different file manager to make sure, I'd remove udisks first and try moving some files with mv tool.

I get the same weird behavior with Cinnamon. Says it copies a lot fast then slows down about 3/4 way through and says it goes really slow. BUT the copy time is pretty normal. I have been too lazy to look into why this occurs, but would like to know if someone happens to figure it out.

Busy copying allot of video files, and it's nice to know if I have 30 seconds to go, or whether it will be 45 minutes. That is why I got interested in it. I am using KDE. I have some incentive to dig on this, while I am transferring files (haha).

Perhaps the first place I should look is in the KDE bug reports.

Not specifically, but a comparative test is copy a file using midnight commander (mc). Copying in that manner bypasses the desktop overhead. If you are using a stock Slackware then another test is use Thunar for some comparative copy dialog results.

I use MATE and the Caja file manager copy dialog seems sane. Generally though I find copying many files to be much faster with mc in a terminal rather than a GUI file manager. I have noticed this for many years. I don't know why GUI file managers are slower (just slower, not broken or dysfunctional :)).

I've noticed something similar, but it seems to happen only when it's transferring a bunch of small files. It's probably hard for it to calculate the transfer speed when the files are small enough that it can't saturate the interface.

On my somewhat hazy memory of this, it seems like once it starts transferring something bigger, the rates always show up.

My video file copying is mostly large files and large directories. With small files, things go quickly. Where I am noticing things not displaying properly is when transferring large files, like with many minutes transfer times.