There's been one proof of concept basic chrome [1] and it wouldn't be THAT difficult to build a more robust one but I'd be much more interested in seeing it running in Electron so you could run Atom or VS Code since the domains are much more limited and rendering perf is a fairly significant limiting factor in those apps.
[1] https://github.com/glennw/servo-shell
P.S. I've never had perf issues with Firefox like you're talking about. You might want to try cleaning out your profile and if it's not that, you might have addons doing something screwy.