As a mobile app grows in users, features, and contributing engineers, there are often tradeoffs between the performance of the app and the velocity of feature growth. Messenger’s users have high performance expectations, so we’ve had to redefine the way we write mobile infrastructure to maintain that performance while still providing reasonable developer velocity. This talk will dive into some of the approaches the Messenger team has taken, like optimizing our use of SQLite, carefully choosing when we load different parts of the application, and modularizing our dependencies.