I hadn't heard about super fast optical transistors, but a few months ago I was reading about ultra fast transistors that operate at 600GHz.

The idea came to me, to write a x86 emulator in 6502 assembly. Run it on a 6502 CPU built using ultra fast transistors, and boom, you've got a faster x86, just it's an emulated x86, MMU and all!

Typical 6502 instructions take 2-8 cycles if I remember rightly, so as long as it takes under 200 6502 cycles to emulate one x86 instruction, you're beating a 4GHz x86 processor.

I'm sure there are practical problems that make it difficult or impossible in reality. But still fun to think about. :)