Compile-on-install was taking so long that in Android 7, they re-introduced the JIT and have been improving it since.
So on Android 7, ART is an hand-optimized Assembly interpreter, which gathers data to a PGO JIT, which likewise gathers data to PGO AOT when the device is idle.
Afterwards they started to optimize this workflow and optimizations being done, and as of Android P, PGO files are uploaded to the Play Store, which are then delivered to identical devices when they fresh install the APK so that they can reach the AOT step with a good level of optimizations faster.
Compile-on-install was taking so long that in Android 7, they re-introduced the JIT and have been improving it since.
So on Android 7, ART is an hand-optimized Assembly interpreter, which gathers data to a PGO JIT, which likewise gathers data to PGO AOT when the device is idle.
Afterwards they started to optimize this workflow and optimizations being done, and as of Android P, PGO files are uploaded to the Play Store, which are then delivered to identical devices when they fresh install the APK so that they can reach the AOT step with a good level of optimizations faster.
Just follow all the links available on the left sidebar here, https://source.android.com/devices/tech/dalvik
There are also a couple of Google IO talks for Android 7, 8 and 9 talking about some of these changes.