File deletion can be expensive/take time on some filing systems.
Dafilesrv has the concept of normal 'fast' traffic, consisting of e.g. many read and write packets from clients and slower atypical traffic, e.g. file copy, treecopy, file append, get crc.
Currently 'remove' is categorised as part of the normal, meaning that if a series of removes take time the available concurrency slots will be occupied and normal trace (standard read/writes) will be delayed.
It would be better to re-categorise 'remove' transactions to the atypical queues, so that they can't delay standard transactions.