Technically there are a few extra tricks you could pull off in microcode if you natively support the instruction set, that even a sufficiently smart JIT compile

Technically there are a few extra tricks you could pull off in microcode if you natively support the instruction set, that even a sufficiently smart JIT compiler cannot. It would be similar to what ARM tried with Jazelle way back when, with some very modest performance gain at best. Not worth the time.