Total Commander

Any chance for option "Show removable drives only with disk" ?

Unfortunately there is no easy way to determine whether a drive is empty or not - TC would have to read from the drive, and this can take from just a fraction of a second to several seconds or even minutes, depending on the drive and its device driver...

And if you check it in a background thread?

That thread wouldn't be faster than in the foreground.

They could be disabled dynamically. Normally the results should be available fast.