I used to share this sentiment (and I’m a web performance consultant by profession so very few people care about performance as much as me!), but when you consider how much calculation we _happily_ let our JS do at runtime, I don’t think forcing CSS to be static/preprocessed is worth it. And that’s not even me taking a swipe at overly-JSsed front-end; I’m talking about any runtime work that JS picks up.

Is preprocessed CSS faster? Yes. Is it meaningfully faster? Probably not.