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Blocking CSS/JS Requests

Blocking (or render-blocking) requests are requests for CSS or JavaScript files that the browser must download, parse, and execute before it can continue rendering the rest of the page. These resources are a major cause of slow load times because they block the Main Thread and delay the First Contentful Paint. A key performance strategy is to eliminate or minimize blocking requests.

Fabian Krumbholz
October 9, 2025
1 min read
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