Nolan Lawson

Does shadow DOM improve style performance?

Screenshot of “Does shadow DOM improve style performance?”

This article is about style performance improvement with Shadow DOM, but it also contains a useful comparison of selector performance between ids, classes and data attributes:

ID and class selectors are fast enough that actually it doesn’t matter much whether shadow DOM is used or not – in fact, they’re slightly faster without shadow DOM. This indicates that systems like Svelte, CSS Modules, or good old-fashioned BEM are using the best approach performance-wise.

This also indicates that using attributes for style encapsulation does not scale well compared to classes. So perhaps scoping systems like Vue would be better off switching to classes.

  1. screenshot of Why We're Breaking Up with CSS-in-JS

    Sam Magura

    Why We're Breaking Up with CSS-in-JS

    Thanks for reading this deep dive into runtime CSS-in-JS. Like any technology, it has its pros and cons. Ultimately, it's up to you as a developer to evaluate these pros and cons and then make an informed decision about whether the technology is right for your use case. For us at Spot, the runtime performance cost of Emotion far outweighed the DX benefits, especially when you consider that the alternative of Sass Modules + utility classes still has a good DX while providing vastly superior performance.