Edit: the post I was replying to was deleted. Guess I should have quoted.
I’d assume it’s an call to a script outside of the main code for the page, which doesn’t always load fast enough if the site (or the user’s internet) is running a bit slower than usual. Not really a bug, and not really fixable for 100% of situations.
On a sidenote, you’re going to love what’s coming next for Kong profiles. And by ‘love’ I mean ‘not love’. Though I don’t really know what profiles even had to do with this topic in the first place.