Rebit does a continuous check of removable media in the background. When a floppy drive is present at the machine, this results in nasty noises.
As the floppy drive of a desktop computer isn't easily "disconnectable", a software function to exclude specific drives from the check would solve the problem.
I'm suspecting some USB card reader driver to slow down the PC, too. This happens when no card is present and the check occurs. This would be solved by the above feature, too.