low-end-device-performancelisted

# Low-end device performance ## The constraint The reference device has 1–2GB of RAM shared with the operating system, a CPU roughly a quarter as fast as the phone in your pocket, storage that is almost full, and a four-year-old battery holding perhaps 60% of its original charge. It is running a browser with eleven tabs and three chat apps that all hold wake locks. Your process is a candidate for termination from the moment it is backgrounded. Performance work here is not about being fast. It is about **surviving**: not being killed, not running out of memory, not freezing the one thread that handles touch. ## Hard rules | ID | Rule | Severity | |---|---|---| | PERF-001 | Name a reference device at tier C and make it the definition of "works". | critical | | PERF-002 | Assume the process will be killed at any moment and restore state on return. | critical | | PERF-003 | Bound every in-memory cache, especially image caches. | critical | | PERF-004 | Keep long tasks off the main thread; never block input for more than 200ms. | warning | | PERF-005 | Recycle or virtualise any list that can exceed one screen. | warning | | PERF-006 | Precompute on the server what the device would otherwise compute. | warning | | PERF-007 | Cap background work, wake locks, and polling. | warning | | PERF-008 | Animate only compositor-friendly properties, and honour reduced motion. | advisory | | PERF-009 | Give any on-device inference or heavy computation a server or static fallback. | adviso