I'm going to nitpick. Instruction sets matter as long as caches are fixed size. The real benefit of x86 is that the instruction encoding is very dense, making

I'm going to nitpick. Instruction sets matter as long as caches are fixed size. The real benefit of x86 is that the instruction encoding is very dense, making the L1 cache more effective. There is not an x86 emulator in software. Microcode is not, and has never been, considered software. x86 needs a complicated decoder, and some infrequently used instructions can turn into hundreds of uops, but that doesn't make it an emulator. There are ARM cores that use instruction cracking and uop fusion. That doesn't mean it's an ARM emulator on top of a highly optimized microcode instruction set. It's an implementation detail.