Firefox is like 10% Rust, and is millions of lines of code. You cannot say "firefox feels slower now, must be the Rust" without actually showing that it's the Rust code.
Every benchmark of the components individually showed improvements when moving to Rust.
Yeah, I'm very surprised with this statement, coming from someone I'd guess should be knowledgeable enough. Benchmarks claim otherwise, and I don't think there's a single overhead you cannot escape from using unsafe. I'm not sure what this person is talking about TBH
Why they didn't do it during their push to Itanic or when they shot their feet helping generic PCs to gain SGI-level graphics is criminal.
Remember NeXT, who made 68K machines, ported NEXTSTEP to x86, SPARC, PPC and HP-PA.