The find based methods in slashroot article are somewhat dubious. Firstly, -exec rm {} \; option will invoke rm for each and every file (also noted by the author). Gnu find offers a nifty feature for such occasions.

$ time find ./ -type f -exec rm {} \+
real    0m1.764s

Which builds up argument list, passing that to rm. It's more or less equivalent to the following (except there's no pipe/xargs involved):

$ time find ./ -type f -print0 | xargs -0 rm
real    0m1.321s

Using -delete:

$ time find ./ -type f -delete
real    0m0.795s

In parallel:

$ time find ./ -type f -print0 | xargs -0 -P4 -n10000 rm
real    0m0.571s

Perl versions:

$ time perl -e 'for(<*>){((stat)[9]<(unlink))}'
real    0m2.917s
$ time perl -e 'unlink for <*>'
real    0m2.308s

Tests were run in a tmpfs backed directory; files created as in the reference article:

$ for i in $(seq 1 500000); do echo testing >> $i.txt; done