I don't think there is such a setting.
I have used the menu item [font='courier new', courier, monospace]Cell -> Delete All Output in some cases, but note that this deletes all generated output cells (including Print cells) and there is no undo on this operation. Another thing I sometimes do is making sure I save to a local drive (in my user account the default save directory is a network backed drive which can add to the notebook save time). Finally, you may want to consider using [font='courier new', courier, monospace]ImageResize[ image, width ] on large images before you output them. That way the output cell can contain a much smaller version of the image for display, which should help with the file saving performance. And if you want to inspect an image up close you can always still use [font='courier new', courier, monospace]CreateDocument to create a temporary notebook document with the full size image (which you can then close without saving).