I have been doing a test implementation of File and Removable Media Protection (tried both 4.3 and 5.0), and have been seeing some extreme performance issues. ~60-90 seconds to open simple text file. The recommendation is apparently to disable opportunistic locking, but from what I've read, this is only possible in SMB1, and cannot be disabled in SMB2 or 3.
I have tested disabling SMB 3 (Server 2012 R2 server) completely and forcing SMB1, and indeed this has cured my performance issues. However I'm not sure if I'm comfortable with this solution going forward. Seems a little ridiculous that this product would be reliant on Windows XP-era technology. Just wondering if this is common, the recommended configuration, or maybe there's something else I'm missing that might explain the issue?