I particularly like the Geometric Humanist stack:

font-family: Avenir, Montserrat, Corbel, 'URW Gothic', source-sans-pro, sans-serif;

Look at how nicely it renders across all the different major operating systems:

It’s also impressive to me that all the major operating systems ship some sort of handwriting font that is half decent.

Use text-wrap: balance; on headings and subheadings. And use text-wrap: pretty; on paragraphs of text to get rid of orphans on the last line. Despite the Chromium-only support, these would be a good candidate for progressive enhancement.

The performance impact is generally negligible but there in extreme conditions.