Have you examined the build artifacts of a site using tailwind? The size of the CSS is often smaller than the same styling in "normal" hand written CSS. There are a dozen blog posts from large engineering orgs that have confirmed that switching to Tailwind slimmed their builds down. Shopify has been a big proponent of Tailwind and they are absolutely obsessed with shipping as little code as possible because of the scale they operate at.

Also, browsers are insanely good at parsing and applying CSS. You need hundreds of thousands of unique selectors before the browser takes more than fraction of a second to parse and render an entire CSS file.

https://www.trysmudford.com/blog/i-spent-a-day-making-the-we...