Understanding Gap Buffers in Jetpack Compose: The 60-Year-Old Algorithm Powering Modern Android UI

Gap buffers, a 60-year-old data structure originally used in text editors, power Jetpack Compose's UI performance through the Slot Table mechanism. The article explains how gap buffers achieve O(1) insertion/deletion by maintaining a movable empty space, and how Compose applies this concept to UI trees for efficient recomposition. Practical optimization techniques include maintaining stable UI structures, using remember and derivedStateOf for expensive calculations, providing stable keys in lazy lists, and batching state changes. The combination of gap buffers for text editing and slot tables for UI updates enables fast Android app performance.