I have a viewport - a section through a site model - that takes AGES to update. It is the section geometry VW is struggling with rather than the rendering (it is OpenGL).    This is what it does to my RAM:     Then after it's finally updated the memory stays at that level in the activity monitor. I have to close the file + reopen it to get things back to normal, until the next edit I make to the VP... Or I get the spinning beach ball + have to force quit.