Performance work fails when it is a cleanup task. It succeeds when a number is agreed up front and a build that exceeds it does not ship.
Pick three numbers
Cold start to first meaningful paint, 95th-percentile frame time, and background battery draw per hour. Three numbers a whole team can hold in its head.
Enforce them in CI
A budget nobody measures is a wish. Instrument a real device in CI and fail the build on regression, exactly as you would for a failing test.
Spend the budget deliberately
Budgets are not about always being fast. They let you say yes to an expensive animation because you know precisely what it costs.
