You'd need UBsan as well, and even that doesn't catch everything. Regarding memory usage/slowness: why not OCaml, D, or Rust?
Rust only recently hit 1.0, so it's pretty obvious why somebody would not have built their software using that.
Also, current benchmarks show Rust to be about ~3x slower than C, making it more comparable to Go or Java.
Interesting. Do you know of any good, recent benchmarks of Rust? I haven't seen a whole lot. The Benchmarks Game mostly appears to show Rust being closer than that in general, though the Rust benchmarks seem to be kind of crap.
A few months back, we were beating C on some benchmarks, though with the focus on semantics for 1.0, I'm sure there were some regressions.