Thanks for the suggestion, I didn't knew about this before! So I've tried it, the lib is small (~9MB on OS X), it renders pretty fast and has python bindings which is quite great.

However it lacks in some areas, such as the scrolling which is quite bad, and it does not render the SVG files that I'd need it to render (tiny SVG spec, but lots of defs and rotations). I'm still going to look better into it since I can use Cairo and CairoSVG to convert my SVGs to PNGs, but I still do not know how well it renders some css rules, fonts, etc..