SceneCanvas performance improvements #1991
Description
This is a revival/continuation of #628. A lot of work has been done to the SceneCanvas since this original issue was made so I'm not sure how much of that original discussion and the concerns put there are still an issue. Scene graphs in general are meant to figure out the order that things should be drawn so they can be done in the best way possible. VisPy's generic/module nature can make this difficult at times. This issue is meant to discuss what it would take to improve the scene's performance and layout where the bottlenecks are right now.