Install the CSS Gzip module

Drupal handles separate CSS files per module. This way module maintainers can provide their custom CSS. But the disadvantage is you get a lot of CSS files. Each file requires a separate HTTP request. The CSS Gzip module extends Drupal's core CSS handling.

Drupal can automatically optimize external resources like CSS and JavaScript, which can reduce both the size and number of requests made to your website. CSS files can be aggregated and compressed into a single file, while JavaScript files are aggregated (but not compressed). These optional optimizations may reduce server load, bandwidth requirements, and page loading times.

Advantages

  • Faster than mod_deflate
  • Faster user-end load times

Disadvantages

  • Requires clean URLs to be enabled
  • Requires public download method

References