Five Jetpack Compose optimisation tips from a junior Android developer

After a while wrestling with Jetpack Compose, I collected five practical lessons that made my code smoother, cut unnecessary recomposition, and noticeably reduced lag on complex screens.

1. Avoid unnecessary recomposition

• Read only the state a composable genuinely needs
• Use derivedStateOf to cache computed values
• Split state into smaller pieces so recomposition stays local

The difference is most obvious on screens with many UI elements.

2. Use remember in the right places

Reach for remember when you have:

• A local mutableStateOf
• A computed value
• An object that does not change (Paint, CoroutineScope, and so on)

Do not use it for values that change constantly — the current time, for example.

Using remember in the wrong place causes bugs that are genuinely hard to track down.

3. Always pass key in LazyColumn / LazyRow

• Add key = { it.id } for every item
• Item state stays correct when you add, remove or reorder the list
• Prevents broken animations and UI jumping around

4. Handle side-effects properly with LaunchedEffect and DisposableEffect

A side-effect should run when its key changes, not on every recomposition.

• LaunchedEffect(key) — network calls, logging, animation
• DisposableEffect — setup and cleanup (listeners, lifecycle)

This is where I hit the most recomposition bugs myself.

5. State hoisting

• Lift state up to the highest sensible parent composable
• Keep child composables stateless
• Pass two things down: value and onChange

What you get:

• Easier testing
• Easier reuse
• Fewer callback-related bugs

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What about you? Do you run into unnecessary recomposition more often, or forgetting key in LazyColumn?