Solid Explorer Classic and Solid Explorer 2.0 are very slow at deleting (folders with) many files. It varies between some seconds for just one file to round about 7 files per second - and this is way too slow for a modern file manager. Android's built-in file manager removes thousand of files within seconds.

A quick Google research shows faster methods of deletion in Linux and a command like this should (maybe) solve the problem:

find <path> -name * -delete

Files will be instantly deleted instead of transferring them to rm at first.

It would be nice, if you solve the problem of slow file deletion.