I was paying attention to a different window of Firefox (v68.0.1) when I noticed a banner saying “A page is slowing down performance” appear in a window for a notebook I had open behind it. The notebook in question was the only tab open in that window, so I profiled its performance after refreshing it, and I was surprised by result. In spite of the fact that there were no
setInterval calls in any of the notebook cells, the former was being called around 30 times per second, and the latter was being called three or four times in the same time frame.
I wasn’t sure if a module I had loaded or errant piece of my own code was the culprit, so I profiled the five-minute introduction notebook, only to discover the exact same behavior replicated there, even after commenting all of the generator cells and cells containing explicit
It’s mildly troubling that none of the
setInterval calls seem to have corresponding
clearInterval calls, as I have to imagine that intervals continue to get created long after the window I profiled the page performance for, but I’m sincerely wondering if this is intended behavior, or something unexpected. Page responsiveness remains remarkably fluid throughout this (until Firefox reports that it isn’t), but it strikes me as an unusual thing to be happening within a system that otherwise seems built entirely on the
Does anyone have any insight into what’s going on?
EDIT: by comparison, the readme page for Observable’s stdlib makes 0 calls to any functions when I profile it, so I have to assume this is the work of a script (or scripts) loaded by every notebook