Initial comments as I write this are all negative, and also responding to something the blog post didn't claim. The only time it says faster than C is when talking about a language targeting the GPU; it is not controversial that GPUs perform better than CPUs for many workloads.

On the other hand, the results of this true fact are already seen in practice in real systems. Rust's iterator adapters, for example, allow high level "functional style" with closures to be compiled to code that is exactly the same as hand rolled C loops without unamortized bounds checks - despite guaranteeing the absence of out of bound accesses even in the face of programmer error - because the constraints of these interfaces and the design of the language enable tons of optimizations by LLVM. This has been true since Rust 1.0 more than a decade ago, it's not a promise of the future.