Ok, checking the current rendering code of the ScatterSeries, there seems to be a lot of room for tuning when moving from "all-purpose" towards "tailored for many points". I guess, a custom implementation that strips the ScatterSeries to a bare minimum might be a good third option.

I managed to render onto an image following the PolarHeatMapSeries example. Current results are kind of disappointing, order by performance:

1. Standard ScatterSeries with binsize 2, plus markers of size 0.75 has mediocre performance (~15 FPS). However, it does not look right: crosses are not points, binsize 2 creates scattered view independent of zoom.
2. Custom implementation looks like a laser scan point cloud, but pan/zoom performance is worse (~7 FPS on a recent gamer machine). No custom binning used so far. There would be a lot of overlap on standard zoom levels (or little to draw with high zoom).
3. Circles with binsize 2 are slower (as the documentation advertised).
4. Without binsize all breaks down. 2-5 seconds per frame.

I can see two options from here:

• Implement custom bin reduction in my custom series, via kd-tree (?) Have to check, how oxyplot does this bin magic.
• Implement custom "point" marker. Not sure how much performance gain is possible when drawing just a line of minimalistic length instead of two lines (cross / plus)

<please insert your terrific idea here> :-)

PS: OxyPlot ist still amazing for all other use cases. Great MVVM pattern in the WPF libraries.