When opening the map on Firefox/Linux zooming to like a France-size view and then not doing anything, the view keeps scrolling up and down relatively slowly, but very annoyingly.

Zooming all the way out, it looks like the globe is jiggling back and forth ever so slightly, but continually.

I've recently seen this happen on another mapping application ( cannot remember which one) so it's probably in down the stack somewhere in a library you are using.