It has to do with the way fsync works and metadata updates on directories. Linux does a lot more work updating directories, which hurts performance on mail se

It has to do with the way fsync works and metadata updates on directories. Linux does a lot more work updating directories, which hurts performance on mail servers in general but really hurts with qmail. Practically you might find your CPU utilization is 2%, but the load average is 50 and you do 'ls' on a directory that has 20 files in in it and it takes 30 seconds.