Moving a directory within a single volume, or simply renaming it, should be an instantaneous operation. However, DLP's copy file hook treats these operations no different than copy and descends into the directories and goes on a scanning spree. I'm attaching a screen grab from an event trace that was taken while DLP was locking up Explorer after renaming a directory containing a fair number of files.
The file copy hook should be smart enough to realize that it doesn't need to scan when renaming a directory or moving it within a single volume. It would nice if it wasn't so slow as well.