[esprehn]

The good news is all modern browsers use a Bloom Filter to quickly skip over elements that wouldn't match the descendant or child selector relationship.

You could probably construct situations with very deep selector relationships and thousands of matching elements where the ancestor walking adds up but the other costs of computing style often end up being more important than the selector matching in many scenarios. Not that you shouldn't aim for simpler selectors of course.

(Usually the problems with expensive selectors come from side effects of dynamic changes to the document. ex. Some selectors will make the browser recompute hundreds of elements when only changing something small because the browser isn't tracking that relationship in a precise way.)

[no_wizard]

Hmm so what’s consensus then? Avoid these types of selectors when at all possible or no?