Empty directory quickly

In order to empty a directory in Linux as fast as possible, there are the following fast possibilities:

1. The fastest way is as follows:

   mkdir /empty_dir
   rsync -a --delete /empty_dir/ /unterordner/Zielordner/

2. If it takes a little longer, deletes all files in the open directory:

   cd /unterordner/Zielordner/
   for i in ./* ; do rm $i ; done