ALL files go through encryption and decryption process when they are copied to an external hard drive. Sensitive files as per DLP remain encrypted and all other files are decrypted after they are copied.
All other files should not have to go through an encryption and decryption process when they are copied to an external hard drive. Only sensitive files as per DLP should go through the encryption process when being copied to an external hard drive.
Symantec Endpoint Encryption Removable Storage is working as per design since version 8.2.1 MP9.
Symantec Corporation is committed to product quality and satisfied customers. This issue is currently being considered by Symantec Corporation to be addressed in a forthcoming version or Maintenance Pack of the product. Please be sure to refer back to this document periodically as any changes to the status of the issue will be reflected here.
Symantec Endpoint Encryption Removable Storage v8.2.1 MP11
Symantec Data Loss Prevention v12.