Website performance doesn't impact the user experience

[chillu]

Overview

As a demo evaluator with a technical focus, I want to be confident that the CMS can produce a fast-loading user experience on the frontend

Acceptance Criteria

• The toplevel pages have at a Lighthouse performance score of 80 or higher
• The homepage has less than 500kb of page weight excl. images
• Images uploaded by users are resized automatically to avoid weighing down the page load time (e.g. for carousels)

Notes

• We should consider using a CDN with asset cache lifetimes
• The CDN should be configured with HTTP/2 for fast network performance
• The CDN should be configured to compress images in modern formats automatically - see https://www.cloudflare.com/learning/performance/glossary/what-is-an-image-optimizer/
• We should consider HTTP cache response headers
• A custom frontend build could help reduce the amount of JS and CSS loaded (currently two for starter theme, two for bambusa theme, and probably some for the demo customisations?)