configuring-lazy-prefetch

Create the window with the LazyLayoutCacheWindow(ahead: Dp, behind: Dp) factory and pass it through rememberLazyListState(cacheWindow = ...), then give that state to LazyColumn. It requires Compose Foundation 1.9+ and @OptIn(ExperimentalFoundationApi::class) at every call site.

First measure with Macrobenchmark FrameTimingMetric on a release build with R8 on a real device. Ensure items have stable keys and contentType, then widen the prefetch cache window only if composition is the confirmed bottleneck.

No, the cache window is not a parameter on LazyColumn, LazyRow, or the grid composables. It must be plumbed through rememberLazyListState(cacheWindow = ...) or the equivalent grid state factory, then passed via the state parameter.

Pausable composition in prefetch is enabled by default in Compose Foundation 1.10+. The prefetch composer can suspend mid-item near the frame deadline and resume on the next idle frame, so upgrading is preferred before manually tuning windows.

Avoid widening when items are cheap, when item composables are non-skippable or unstable, or when measure/draw dominates rather than composition. Wide windows raise memory pressure and waste prefetched work on direction reversals without fixing the root cause.

The outer prefetch only warms the row's outer composition, so the inner HorizontalPager's first page composes on the user's first swipe. Implement NestedPrefetchScope so the inner layout's first item composes during the outer prefetch slot.