We notice some fairly significant performance slow-down as we initialize our diagram (specifically when switching what the diagram shows and doing mass additions/removals). The Thumbnail seems to be creating lots of WriteableBitmaps over and over at that time (specifically in BitmapUtils.CreateWriteableBitmap). This seems to happen the first time we use the diagram (say, 40+ invocations of CreateWriteableBitmap) but only once thereafter when we do wholesale changes of what we show in the diagram.
I initially thought it's something we do, but I don't find any difference between the first time we populate the diagram with shapes and subsequent times.
The call to CreateWriteableBitmap is triggered (ultimately, through several steps) by RadDiagramThumbnail.DeferredRefresh.
1) Is there any built-in functionality to limit the rate at which Thumbnail updates itself? If not, do I read the documentation correctly that we should expect to be able to use IsAutoRefreshEnabled and RefreshThumbnail to rate-limit the Thumbnail refreshes ourselves?
2) Any advice for further tracing/debugging why we see so many calls only the first time we populate the Diagram? Or, other things that we might be doing differently between the first time we populate Diagram and subsequent times?