"Observe how he never brakes, even when you're certain he should"
Regarding the Porsche, I doubt it would have been useful. The car maxed out at 369km/h, and was unable to maintain the speed for long. I doubt it has the torque to pull further ahead in an eighth gear. Furthermore, the heavier gearbox would weigh the car down for the entire race, and the shift to eighth would by itself cost the car a little bit of time.
It seemed like everything was actually quite well balanced. It was only maxed out for a tiny moment, so it seemed to be the perfect balance between lightweight and brute force.
As the saying goes, "Don't judge a book by its ISBN."
Sounds like that's how long he's been chasing a sub-10-minute lap