Simple case of not guarding against duplicate settings in the setter methods in Scenario. In particular, setMode() on SGAbstractShape showed up a lot in profiling. The problem is that for the most part FX filters out duplicate settings, but in situations where FX doesn't do this, we end up invalidating the tree, repainting, accumulating dirty regions, and recomputing bounds even if the property hasn't actually changed. Simply need to guard in the setters. This alone accounted for up to 16% of the time in the bond demo.