My experience has been that it turns out that rendering isn’t usually the bottleneck. If you have a complicated 3-d volume the data for that gets send directly to the browser via webgl and that goes directly to hardware.
The big bottlenecks that I’ve seen are due to network. Redraws are fast, but I have a suspicion that what might be happening is that every time you scroll, something is being sent over the network and the client is waiting for something to come back.