Users do not read your changelog. They notice that the app opens before they can look away.
We hold a cold-start budget of 1.2 seconds on a mid-range device and enforce it in CI, alongside install size and crash-free rate. A build that blows the budget does not ship; it gets a ticket like any other regression.
The work is unglamorous — deferred initialisation, baseline profiles, fewer things on the startup path — but it moves day-30 retention more reliably than most features on the roadmap.