Set the point threshold for when a series should enter boost mode.

Setting it to e.g. 2000 will cause the series to enter boost mode when there are 2000 or more points in the series.

To disable boosting on the series, set the boostThreshold to 0. Setting it to 1 will force boosting.

Note that the cropThreshold also affects this setting. When zooming in on a series that has fewer points than the cropThreshold, all points are rendered although outside the visible plot area, and the boostThreshold won't take effect.