How R8 made Kotlin Coroutines on Android 2x faster

Published on: Aug 03, 2026

Android Toolkit and Jonathan Starup, Software Engineer, R8 Team Starting from AGP 9.2.0, R8 optimizes most Atomic*FieldUpdater calls into Unsafe variants that perform 2x to 4x better on common operations. This has a particularly large impact on the kotlinx.atomicfu library that implements atomics for kotlinx.coroutines, making launching and cancelling coroutines up to 2x faster.