I was very critical of Mozilla in the past about all their "science projects" like Rust. While I appreciate Rust, I thought it was wrong for Mozilla to be wasting resources on it, instead of focusing on Firefox.

I was so harsh with them only because I strongly believe that Firefox is my only hope for a free web.

But then I tried 57, and I must admit, boy was I wrong. This thing is fast! I haven't stopped recommending it to friends and colleagues!

Good job folks!

Rust was pretty much designed to solve problems for Firefox. It's IMO the best bet Mozilla has made these last few years and we're just starting to see them reaping the rewards.

How much Rust is actually in the new Firefox? I'm not seeing any based on a casual click-around in the repo, though I'll freely admit I haven't scanned the entire source tree.

Edit: if there is any, can someone give me a link to the part of the source tree that has it?

I don't know if there's any one location for all the Rust code; it may not make logical sense to put the MP4 parser written in Rust right next to the CSS engine, for example. I believe that https://github.com/mozilla/gecko-dev is a mirror of the repo in question, and so we can use Github's search function to find every file that it detects as being a Rust file: https://github.com/mozilla/gecko-dev/search?l=rust (which finds 3,274 Rust files, 6,701 C files, and 22,722 C++ files).