The ideal setup for performance: Gatsby with Drupal 9


A slow website means a bad user experience, a high bounce rate, and SEO penalties

Slow loading times can be caused by several factors, including poorly written code, outdated technology, large image files, too many external scripts, and poor hosting services. 

When your site is slow, especially the mobile version, Google factors that in and could penalize your site's quality score which will have a negative impact on SEO.  Not to mention bounce rates and overall user experience.