[zrm]

Probably the fastest processor made on 130nm was the AMD Sledgehammer, which had a single core, less than half the performance per clock of modern x64 processors, and topped out at 2.4GHz compared to 4+GHz now, with a die size basically the same as an 8-core Ryzen. So Ryzen 7 on 7nm is at least 32 times faster and uses less power (65W vs. 89W).

You could probably close some of the single thread gap with architectural improvements, but your real problems are going to be power consumption and that you'd have to quadruple the die size if you wanted so much as a quad core.

The interesting uses might be to go the other way. Give yourself like a 10W power budget and make the fastest dual core you can within that envelope, and use it for things that don't need high performance, the sort of thing where you'd use a Raspberry Pi.

[snovv_crash]

You wouldn't get access to ASIC fab just to make a CPU. Fill it with tensor cores, or fft cores, plus a big memory bus. Put custom image processing algorithms on it. Then it will be competitive with modern general silicon despite the node handicap.

[yummypaint]

Your suggestion was more what i was thinking, perhaps something more limited in scope than a general processor. An application that comes to mind is an intentionally simple and auditable device for e2e encryption.