With the latest weekly which includes the Tippy.js PR (https://github.com/jenkinsci/jenkins/pull/6408) we are seeing very long loading times on our instance (~30 seconds for the main page).
I did a performance recording using the Chrome and Firefox dev tools and both show that calls to registerTooltips take a very long time. I am attaching a screenshot.

I am assuming that this is related to the PR mentioned above but of course cannot be sure (especially because I am not a web/javascript developer myself).
Please let me know if there is anything I can provide or should do to support you in solving the issue (e.g. provide some data, try things out).