> Grand Theft Auto V is a 100GB install on my computer, but it runs at a buttery smooth framerate on modest hardware.

I mean you're not wrong that install size != slow performance, but GTA5 is a funny example for being the game that had 6 minute loading screens to start online mode until someone reverse engineered it and found it was mostly from parsing a giant 10MB JSON blob, and reduced the loading time by 70% with a small patch.

Very possible the bad priorities lead to both the ginormous install size and the fact that no one internal was tasked with fixing the load times.