Even crazier, my i5 750 (from 2009) was overclocked to 3.5ghz and per core Ryzen 3 isn't even twice as fast.

We're near the end of IPC scaling per core. And it was never that good in the first place. Pentium 3 IPC is only 3-4x worse than the fastest Ryzen. Most of our speed increases came from frequency.

IMO we need to get off silicon substrate so we can frequency scale again.

I wonder if the end of scaling will push everyone into faster languages like Rust. You can't sit around 2 years for your code performance to double anymore. Will this eventually kill slow languages? I think so.