A measure-first playbook for senior Android engineers, built around a ferry departure board that kept missing frames.

Every performance story in Compose eventually collapses into the same two sentences. Somebody noticed jank. Somebody else rewrote something clever, and the jank either stayed or moved to a new place.

This post follows a fictional app, Quayside , a live departure board for a harbor ferry operator. It has a long scrolling list, a “jump to top” button, analytics on berth views, and a tide chart fed by a few thousand samples. Each section takes one optimization from the recent Android Developer Summit talk Outperform yourself in Compose and shows what it costs when you apply it carelessly. The goal is not a bag of tricks. It is a habit: predict, measure, keep or revert.

A note on versions. The examples use computedStateOf , which arrives in Compose Runtime 1.13, and keyed SideEffect , which arrived in 1.12.…