I have a Pioneer BDC-207D BD-ROM that I use with MakeMKV for BD's only.
When installed internally it would be pretty slow. The best it could do was slightly over 3x and would degrade to below 2x.
Sometimes a BD would be locked at 2x for the entire duration.
Just recently I decided to install the drive in my Vantec USB 2.0 5.25" enclosure and it has been performing a lot better in it.
At the beginning of a BD it would get to 3.5x in a matter of seconds and steadily increase to 5.2x. It stays at 5.2x for a bit then quickly reduces to 4.5x and ending at about 4.7x.
Is there any reason why this BD-ROM rips faster externally rather than internally?