Hi, this is not really an issue, I know but this is the only section where it seemed appropriate to post my findings.

I'm running a DVD version of Morrowind from way back and recently added a shortcut in Steam to check if the overlay worked which it did. As a side-effect, I gained about 10 FPS in performance-heavy areas. My new character has just begun exploring Tamriel Rebuilt's landmass and is currently in Akamora. If I run Morrowind outside of Steam, I average about 15-20 FPS when moving about there, running through Steam gives me a comfortable 25-30 FPS and higher in areas that are less densely populated with stuff.

It might just be my system that benefits from this and I'm not entirely sure why it happens but I'm not complaining. I just thought I'd put it out there as it might helps others squeeze out a bit more performance from this old gem.