You are copying files or folders onto a USB or Removable Storage Device and you find that it takes an excessive amount of time.
Policies which include compound exceptions, two-tier detection (see What DLP Rule Conditions Will Cause Two Tier Detection), or regular expressions can require more time than a simple keyword policy in detection on the Endpoint Agent system. In some cases latency will depend on your system CPU, Memory and USB speed e.g. 1.0 or 3.0. To determine the exact cause of the excessive latency you will need to do some initial investigation.
To investigate this issue break it into two areas (i) Resources and (ii) Policies then check the following:
Resources:
Policies:
For assistance on policy tuning please refer to Best practices for authoring policies.