I was just playing with the Speckle Revit plugin. I have developed similar plugin in past for exporting the Revit data. I just noted that for each family instance you are creating the separate set of mesh data this will create the memory issue and slow down rendering. When model contains say 1000+ family instance. You can use the transformation matrix that Revit providing and keep the single instance of mesh data. You can render the family instance runtime using the transform matrix. This will make application efficient. You might be using internally ? but while exporting through the speckle REST api I get different mesh data for each family instance.