Page is excessively heavy

What this means

Either the document itself is very large or it pulls in an unusually high number of subresources. Both push up memory use, style-recalculation and layout cost on the client, and both slow the render pass crawlers apply to the page.

How to fix it

Split oversized pages, paginate long lists, and consolidate or defer subresources. Audit the largest scripts and stylesheets first — bundle count is usually easier to cut than document size.

Fix effort

This check needs a developer fix: it turns on a routing, hosting or infrastructure decision that no automatic edit can make safely.

Authoritative source

https://developer.chrome.com/docs/lighthouse/performance/dom-size