@skydesigner OK, than you may try to use the ionice command.
Unfortunately, ionice doesn’t work in GUI. There’s no way to improve file operations with it in GUI.
It works for CLI file commands only. And may be used with any of them.
The syntax is very simple. Just preceed any file command with ionice. If a command must be preceeded by sudo, then put ionice after sudo and immediately before the command.
ionice [command] [command-parameters]
ionice cp [source] [destination] -- try to use this one
sudo ionice dd if=[input] of=[output] bs=4M && sync
sudo ionice fsarchiver savefs ...
ionice does for I/O operations what nice does for CPU.
Try it. If it works, I may explain what ionice does more in details.