[edoceo]

How can one even test the performance of these selector? I've been have a few pages that feel slow, and have some exotic selectors, but I've no clue what tools to uses. And searches for CSS performance tell me lame things like: minimize and use a CDN. I have the XY problem.

[mst]

Try adding 'browser' and/or 'layout' as keywords for your searches - that seems to surface stuff about the relevant sort of performance.

(this semi helpful advice brought to you by mst's complete lack of front-end chops meaning concrete help will have to come from somebody else ;)