I use SassC: https://github.com/sass/sassc - a basic SASS/SCSS compiler written purely in C. It's not 100% up-to-date with the ruby version and you miss out on the more advanced features like custom functions, but it's blazing fast and I've never really needed more than the basic features anyway.

My problem there is that Susy Grid requires bleeding-edge SASS. And the very latest Compass version, too.

> The libsass library is not currently at feature parity with the 3.2 Ruby Gem that most Sass users will use, and has little-to-no support for 3.3 syntax.

That said, it is mostly good enough. I've used it for a few SASS projects in combination with Bourbon and it works great. IMO the huge compilation speedup (I saw reductions from 5-6s to about 200ms) was worth the slight move backwards in features. I became much more productive with a more responsive livereload.

Libsass is missing some hugely important features, but it (appears to be) in very active development and the disparity list is shrinking.

Even lacking missing those features, the 12x compilation speed improvement in libsass is pretty compelling.

The note is slightly outdated - the recently released libsass V3[1] is targeting SASS 3.4, and they expect to fully pass the spec by V3.1

Does libsass work 100% with the Bootstrap sass port? Every time I've checked on libsass support it is behind the ruby version in some way.

Yes - we use libsass across the board, including building BS3, and have had no issues with compatibility. It used to have a problem with high precision numeric values (like "6.666666666%" in BS) but that's has been resolved.