Deletion can be much slower than file creation when the files are hundreds of mb too!
Worst of all, "rm -R" runs right into XFS's most pathological case -- it's doing tons of metadata reads while it unlinks files, and XFS shoves a lock in every orifice.
Deletion can be much slower than file creation if the files are small.
If you google for 'xfs delete speed' you'll get plenty of bits of information, the best fix was the 'nobarrier' option.
Deleting files at random is especially bad.