I’m not sure if this issue is specific to just Bokeh or if Panel adds to it, but after upgrading to Bokeh 2.4.0, I’ve been seeing massively degraded performance in quadmeshes & heatmaps when serving pre-rendered charts via Panel HTML pane embeddings.
The left side shows the pre-rendered chart as standalone html file, while the right side shows the same pre-rendered chart embedded via Panel HTML pane.
This used to work fine before the update to 2.4.0.
Was also reported here:
Seems like the same issue is also present in Jupyterlab.