No instant feedback when hovering over a dot on the radar

Currently a tooltip with the name of the corresponding tech is shown with a few seconds delay (at least on Chrome). Skimming through the radar is too slow because of that.

I thought about using bootstrap tooltips but because the dot is generated using Protovis, it may not be possible to put a tooltip there. Maybe putting a div under the radar with the name of the hovered dot/tech would be ok?