> Wouldn't -O3 with -Ofast do all code optimization for programmer.

No?

> Contributor dav1d claims 1-3% growth after his optimization, depending on video dataset payload. He nullified 1% optimization in rav1d, if the real growth was 3%, rav1d will not soon be able to equalize benchmark results.

Aren't you the contributor? (You have a very unique writing voice)

> Another question in theory can Rust be faster than C? If all possible optimizations are applied.

I don't see why not?

Other than that:

A) Great work!

B) Unsolicited advice, apologies: your technical acumen is being outshadowed by projection of motivations.

They're just programming languages.

There's no way to say one is definitely better than the other, and no guarantee one will be faster or slower than the other.

Your forebears had similar arguments about C and assembler.

Yet, neither of us is surprised to find there is no asmav1d. (and that's much more clean-cut of an argument w/r/t speed!)

(I don't think it was the goal of a long-running FOSS project to advertise Rust is almost as fast as C when they offered a bounty)

> Another question in theory can Rust be faster than C? If all possible optimizations are applied.

Very likely not at this stage, and maybe not for years to come. But I'll take increased memory safety and elimination of entire class of bugs for 1-3% performance loss even on the most critical paths (with many actual wins for Rust in many other cases).

While I do get what huge battery life implications might 5% differences in decoders make, I believe the current political climate mandates we use the most secure code we can and sacrifice smidgen bits of performance here and there for it.

It was known for decades that at one point we'll have to roll up our sleeves and pay up the security tech debt.

Sorry for the slightly philosophical message but I've no desire to comment on the actual tech details here.