Our fitness kit's iOS build used to take 14 minutes on CI. After upgrading to Expo SDK 54, it takes 4.
That's not a CI optimisation. We didn't add parallel runners or bump the machine size. We just landed on the SDK that ships precompiled XCFrameworks by default. Same code, same build profile, same EAS plan — 70% time reduction.
Worth understanding what Expo actually changed.
What got precompiled
Historically, every iOS Expo build had to compile the entire React Native core and all native modules from source. Hermes, the Reanimated worklets runtime, the Skia engine, JSI bridges — every one of them rebuilt from scratch on every CI run unless cached.
