« CSS and Network Performance » by Harry Roberts, 09.11.2018
▻https://csswizardry.com/2018/11/css-and-network-performance
Important for Custom Elements / Web Component authors: CSS @import performance is poor; the article describes why, in great detail.
« Summary: lazyload any CSS not needed for Start Render; avoid @import, in CSS especially; be wary of synchronous CSS and JavaScript order; load CSS as the DOM needs it. »