every so often there will be always somebody trying to make a hobby OS that outright ditches native code and uses exclusively bytecode for the programs running on it... Not sure if that actually ends up happening in practice.Android?
Sure, the kernel, the Dalvik VM, and some low-level functionality is written in C/C++, but pretty much everything else is in Java. Of course, game developers kvetched till they were given access to native code, but that's neither here nor there...
Well, it gets jitted, and cached usually...
Still, android is a damn slow platform most of the time, its very annoying. Someone went through and rebuilt the OS with pre-jitting etc. and it was significantly faster than the one that normally ships on phones.
Mind you, its not a problem with JIT or interpreted languages or anything like that. Its simply that JIT + embedded systems don't really go hand in hand very well (they work, but its usually not the best...idea).