It's complicated to do binary caching for various low level reasons. Amongst other things, the generated binary code is specific to the precise location in memo

It's complicated to do binary caching for various low level reasons. Amongst other things, the generated binary code is specific to the precise location in memory and makes lots of assumptions about the state of the runtime like what classes have been been initialized. Still, HotSpot has been slowly (too slowly) getting AOT-like optimizations in the form of AppCDS. It doesn't actually store compiled code but a lot of other internal data structures can be stored to disk in native form and just mmapped at startup. It's usually a 30% win or so, which isn't bad.