This is probably blur related. We should retry after https://github.com/servo/webrender/pull/1961 lands.
I believe #1961 landed and this page is still pretty bad (and renders incorrectly).
This is indeed blur related. The two <a> elements for "IPFS" and for "CRDTs" each have an ::after pseudo element which has box-shadow: -350px -20px 1000px 22px #23e0f7 set on it. That's a 1000px radius blur.
I take a look.
Looks like the performance bottleneck is not box-shadow anymore. I sent a PR 2096 to fix the rendering problem. I will keep investigating the next performance bottleneck in this page.  https://github.com/servo/webrender/pull/2096