I am trying to place small markers on the chart that line up with DateTimes of interest.  The problem is there are very few of these marker points compared to the actual data points.

With XamDataChart there are two ways to plot multiple line series when there isn't an one to one relationship in the number of points of each series and only display a single XAxis.

The first way is to create multiple X Axes and set their ItemSource to the source of each series.  Then set  LabelSettings.Visibility to Collapsed for all but the series that spans all other series (assuming such a series exists).

The second way is to use a single X Axis for all series, set the ItemSource of the axis to one of the series and make every other series match the series that is the axis is bound to by filling in with NANs.

I need a very high performance solution that can be updated in realtime and I don't know if it is more efficient to create multiple X axes (there could be dozens of these) and hide them or if it is more efficent to fill the data in with NANs.  In the latter case this would mean 99% of the marker ObservableCollection would be NANs.

Can someone tell me which has better performance or is there a better way to place markers on a XamDataChart?

I hope this is clear.  Please tell me if it isn't.  Attached is a screen shot that should give you an idea of what I am trying to do.  I've also attached the small app that created this graph.