Rendering performance

[dvmoritzschoefl]

For certain tracks the performance is not good enough to ensure a smooth scrolling & panning experience. I think it is partly because the Pixi.js graphics object is cleared everytime instead of reusing the geometry. There are also patterns which copy the underlying data arrays multiple times (see the filter and map operations in the point mark renderer). We experienced this when using the "point" mark with json data (~500 - 1000 points) but it can also be observed in the gosling examples like this one

https://gosling.js.org/?example=CORCES_ET_AL