Investigate poor LCP stats

[duckduckgrayduck]

During today's outage I noticed in the DocumentCloud Cloudflare page that we were experiencing poor LCP (Large contentful paint) during yesterday's surge in interest in this document:
https://www.documentcloud.org/documents/27886068-hdnawxtw8aauamr/
https://developers.cloudflare.com/web-analytics/data-metrics/core-web-vitals/

This affects performance.

You can see our LCP stats by going DocumentCloud (domains) -> Analytics & Logs -> Web analytics

[allanlasser]

@duckduckgrayduck I believe this is due to the viewer taking up most screen real-estate, and the document not loading into the viewer until seconds after page load. I don't think this is a huge issue, but could be optimized by rendering placeholder pages (or, even better, supporting partial document loading!).

[duckduckgrayduck]

Ok, this view makes it way easier to find what actual assets are causing poor load times and LCP, looks like it is primarily GIFs:
https://dash.cloudflare.com/68641c3e1187cb7318e641504c2780fb/documentcloud.org/analytics/web/overview