Kolibri makes Expo JNI calls 51x faster

Kolibri’s real innovation is moving JNI overhead out of hot paths through compiler rewrites, explicit environment handling, and binary serialization. The headline gains are compelling, though developers should note the benchmarks were measured on a desktop JVM rather than Android hardware.

• –Hybrid-object calls drop from 76–272 ns with fbjni to roughly 2.7 ns with Kolibri.
• –Binary buffers make complex JavaScript-to-Kotlin transfers up to 13× faster.
• –Selective safety features let developers trade automatic cleanup and exception checks for speed where appropriate.
• –The library is purpose-built for Expo Modules 2.0, so its narrower scope is both an advantage and a limitation versus fbjni.
• –Adding another native dependency increases maintenance and app-size costs, but may simplify performance-critical React Native modules.