Bugzilla

I do see a several-seconds-long hang in Firefox when I load that page in GitHub, **after I scroll to the bottom of the page** (e.g. if I press "End" on my keyboard).  GitHub seems to be doing some lazy-load processing to show more of the diff, which locks us up for a bit.

Here's a profile of what I see, for reference:
https://share.firefox.dev/3GzzyWs
There's about 9 seconds of jank in the middle here (though on the plus side, we are reliably painting GitHub's throbber/spinner animation during this time, to indicate that something is happening.)

I do see a several-seconds-long hang in Firefox when I load that page in GitHub, **after I scroll to the bottom of the page** (e.g. if I press "End" on my keyboard).  GitHub seems to be doing some lazy-load processing to show more of the diff, which locks us up for a bit.

Here's a profile of what I see, for reference:
https://share.firefox.dev/3GzzyWs
There's about 9 seconds of jank in the middle here (though on the plus side, we are reliably painting GitHub's throbber/spinner animation during this time, to indicate that something is happening.)

Note, I only get this jank if I'm logged in to GitHub.  If I'm not logged in, then GitHub presumably renders different content that happens to be not as expensive to set up.