Servo is nowhere near ready. It's been a few months since I've seen actual results, but I'd be surprised, if it nowadays completed ACID3 (which was state of the art for browsers in 2009).
The thing is that rewriting a browser engine doesn't just happen over night. No bigger browser engine has been written from scratch since the previous millennium. Also, no browser engine implements all currently specified webstandards. So, Mozilla would have to full-pelt develop Gecko to be able to keep up with Blink in webstandards, and then also develop Servo at more than full-pelt to be able to catch up in finite time.
That just doesn't add up, which is why Servo was specifically started as a research project. It might never be completed. They have been able to integrate various components from Servo directly into Gecko, therefore sharing the development work which they didn't really plan with, so that's one tiny reason to still hope for it to ever catch up, but yeah, just don't be too optimistic.
Having said all that, the integration of components from Servo into Gecko isn't done yet. WebRender is still missing, which should bring another good performance boost. It's sort of been overhyped with artificially complicated CSS animations [0], so the real world effect isn't that big, but it's still very much noticeable.
Aside from that, on Android, Mozilla is building a new framework for building Android browsers in general, called "android-components", which also includes a much cleaner integration of Gecko on Android, called "GeckoView".
They've already rebased Firefox Focus onto GeckoView and are actively working on rebasing Firefox for Android (Fennec) onto it, too, which is internally called "Fenix". This should also significantly reduce the lagginess and speed up their development in the long-run.
I guess, what I'm mainly trying to say is that there's definitely still things happening.
We have them. HTML/HTTP work great, but the DOM and JS APIs are out of control, and their surface area has no end in sight.
The web actually works great without JS, and doesn’t require gigs of memory to browse.
Every month there’s some new JS API being proposed or developed for browsers, with no care for its impact on the web. The JS APIs are still growing and only getting more complicated too! service workers is a perfect example of the problem. Offline browsing worked great 20 fucking years ago, but now multithreaded Turing complete programming languages have to be used to view a website offline. It’s absolutely absurd.
The thing is that rewriting a browser engine doesn't just happen over night. No bigger browser engine has been written from scratch since the previous millennium. Also, no browser engine implements all currently specified webstandards. So, Mozilla would have to full-pelt develop Gecko to be able to keep up with Blink in webstandards, and then also develop Servo at more than full-pelt to be able to catch up in finite time.
That just doesn't add up, which is why Servo was specifically started as a research project. It might never be completed. They have been able to integrate various components from Servo directly into Gecko, therefore sharing the development work which they didn't really plan with, so that's one tiny reason to still hope for it to ever catch up, but yeah, just don't be too optimistic.
Having said all that, the integration of components from Servo into Gecko isn't done yet. WebRender is still missing, which should bring another good performance boost. It's sort of been overhyped with artificially complicated CSS animations [0], so the real world effect isn't that big, but it's still very much noticeable.
[0]: https://www.youtube.com/watch?v=u0hYIRQRiws
Aside from that, on Android, Mozilla is building a new framework for building Android browsers in general, called "android-components", which also includes a much cleaner integration of Gecko on Android, called "GeckoView". They've already rebased Firefox Focus onto GeckoView and are actively working on rebasing Firefox for Android (Fennec) onto it, too, which is internally called "Fenix". This should also significantly reduce the lagginess and speed up their development in the long-run.
I guess, what I'm mainly trying to say is that there's definitely still things happening.