Performance problem with multiple parallel rm -rf's

[Jens Rosenboom]

On a large 13TB XFS volume that is being used for backups, I am seeing 
bad performance if multiple "rm -rf" processes are running in parallel. 
The backups are being done with rsnapshot and the first operation it 
does is removing the oldest snapshot. A single rsnapshot does this in 
reasonable time, but if four jobs are started at the same time, all 
their rm processes run for hours without making much progress.

This seems to be related to the planned optimizations in

http://xfs.org/index.php/Improving_Metadata_Performance_By_Reducing_Journal_Overhead

Are there any other tuning options I might try? I'm already using 
"noatime,nodiratime,nobarrier,logbufs=8,logbsize=256k" as mount options 
and did enable lazy_counters for the fs.