Generating CSS at runtime has performance costs, especially
if your code is in a hot path (and usually with CSS-in-JS that's true
for all your styles). However, the hit isn't more than using dynamic values
styled-components or using
styled-system. We were also very
restrictive about the shipped features to keep the core as primitive as
possible. CCSS on its own avoiding a lot of processing other solutions have.
However, to boost performance YouEye has a Babel-plugin supporting static extraction. It replaces all Ui calls with native DOM elements and class names.
Why just not use
It's not YouEye's goal to have an amount of features
styled-system have. However, the mapping
approach used by CCSS is making the compiler capable of supporting
custom properties and custom values which helps you to create your own custom
design system, ergo: Styled System could be implemented using CCSS.