Update: The issue has been acknowledged by Aspyr. I feel hopeful they will find a resolution for this. While it is unacceptable to put out a game with this sort of performance, I do understand pushing a game out on multiple platforms is very challenging and compromises need to be made to make deadlines for a multi platform release. I also want to note that I personally never played Republic Commando back in the day, so I never got to see first hand how it performed on original hardware.
At the end of the day, I am happy about Aspyr acknowledging the issue even if it wasn't public. I think we will see some sort of resolution soon to address the inconsistent FPS issues.