Page freezes when loading supporters

[j-f1]

Whenever I scroll the supporters list into view, the page freezes for several seconds before becoming interactive again. (Safari Technology Preview Release 135 (Safari 15.4, WebKit 16613.1.7.3, macOS 11.6 (20G165)))

I’ve attached a timeline recording, but it looks like the issue is that it takes a long time for Safari to render the 65,000 character HTML string being injected.

www.11ty.dev-recording.json.zip

I used DOMParser to pre-parse the HTML and confirmed that parsing only takes ~2ms, while inserting the node into the document takes around 12 seconds.