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Plotly.min.js 1.43.1 much faster than Plotly.min.js 1.52.2

I have some python scripts that generate html files every week with over a million points. I was recently updating these scripts and decided to upgrade to the current version of Plotly.py which includes plotly.js 1.52.2. To my dismay, the hovertext when moving the mouse was slow enough that it was unusable, particularly when set to “compare”. I found a copy of the older plotly.js 1.43.1 and ran the exact same script except I forced it to use the older plotly.js and the hovertext was quick again.

There seems to be some kind of major slowdown between these versions of plotly. Is this a known issue? Is there some way to work around this or I will I have to always save my old version of plotly.js? My only concern is that eventually the old versions of the plotly.js will stop working with newer versions of plotly.py and then I’ll have a real problem.

I included the html files here in a zip file so you can compare the performance yourself:

Another minor difference is that the new version of plotly shows the hovertext at the bottom for the event line trace even though there is a perfectly good point in the visible plot area.