I generally lead teams to move quickly to get products usable, deliver the most important features to feed the business, then go back and start optimizing thing

I generally lead teams to move quickly to get products usable, deliver the most important features to feed the business, then go back and start optimizing things like launch times. The DoorDash app is feature stable as far as I can tell as an infrequent user. It makes sense to have the team invest into small optimizations for experience and speed. Much better than letting idle hands start redesigning things that aren’t broken or doing new features for the sake of doing more things. Also, a 600ms launch time on a high-end phone could be a 5s launch time for someone using a cheap, old phone. Optimizations are most noticed by the lower end of your userbase’s hardware.