It should be mentioned windows explorer copy and move operations display a very nice dialog depicting transfer speed. I am suggesting dolphin have similar graph like display for speed of transfer. Would make dolphin more complete and feature full along with improve usability.
The problem is in KIO which manages such jobs. Copy job creates a subjob for every file it copies, however, they only report speed after 1 seconds at which point the job has already finished and the next one started. This is why you can see transfer rate for large files but not when copying many small ones.
As for the graph, that has to be done in plasmashell's notification center (I'm its maintainer and am actually a huge fan of this modern Windows copy dialog) but we first need to figure out how to actually get that data to the application in the first place.
> (I'm its maintainer and am actually a huge fan of this modern Windows copy dialog) +1, me too. It's really nice.
> however, they only report speed after 1 seconds KIO file_unix::copy reports progress 10 times a second or every 512KB, they could some issues elsewhere.