[Yaggo]

It's actually worse on mobile, because mobile connections typically are not order of magnitude slower than non-mobile, but mobile cpu power can be order of magnitude more limited (esp. on lower end hardware).

https://timkadlec.com/2014/09/js-parse-and-execution-time/

[reitoei]

That article is about JavaScript, not CSS.

[Yaggo]

Does not matter, same principles apply to CSS as well. Transferring is pretty lightweight operation compared to parsing & rule applying.