Framerate going all over the place, the game requiring a MUCH higher-end PC than stated in the sysreqs to run it at a remotely decent performance (and even THEN some effects might cause slowdowns), abysmal vehicle handling (as if you're pressuring the analog stick with full force at all times, making some chase missions super difficult), cutscene glitches being a field of science of their own...

That's...interesting. I wonder if some correlation with the computers that have issues running the game might lend a clue to why. I am running Win 10 with an older AMD Radeon card. Not seeing any of those problems.

It was just poor code optimization while porting from the Xbox 360. You got lucky, I suppose. I have a solid rig myself but even with GotR some effects can cause frame drops. I run SR3 and SR4 on max settings without any slowdowns.

I was thinking SR3 is one that's a "port from Xbox 360" rather than SR2. I had no issues at all with SR2, but SR3 seems a bit more janky across the board with:-
- occassional bugs in the game physics such as floating mid-air debris objects, small objects blocking the player from moving, and overall questionable collision detection
- rather crappy vehicle handling
- some terrible npc AI, especially in missions where they drive the car! they get stuck sometimes costing you the mission!
- quite a lot of z-fighting in bulding decals
- Steelport is simply just not as good as Stillwater in SR2, it seems smaller, more claustraphobic IMO - and much blander and less diverse in it's scenery.

Not that it's all enough to make SR3 a bad game, not at all, it's still a good game, but I enjoyed SR2 a more.