Don't know what the speed run record for Fallout 1 is, but it's not at all relevant. Like not even slightly.
You can beat Morrowind amazingly fast if you know exactly what to do, where to go, and how to win against Dagoth Ur.
Pacing only really has much to do with your first playthrough. Of course you can't set a pace for a second playthrough, everyone already knows where to go to get what. Mods, again, completely irrelevant. You can't judge a game based around something that is not part of the game.
Not really sure why you're bringing up 100% completion, mods, and speed runs.