Not just performance, the code was littered with unsafe blocks and the benchmarks (IIRC) were gamed heavily by the Rust people.

It was a dishonest effort that actually undermined the memory safety pitch.

> It was hard to match performance

They say it is 5% slower. That's close enough. I know they say it isn't but in reality that speed difference is just going to be used as an excuse by the anti-Rust crowd.