Toggle Thumbnail Preview 1
Toggle on/off the Nautilus file thumbnail preview
This does not change your preferred view or zoom settings.
After you run the script to toggle on the thumbnail preview, do not forget to refresh the nautilus window (ctrl+r). If you do not, it will appear as if the script did not work.
This should help until nautilus provides the option for directory specific preview settings. It really sucks the CPU when viewing a large directory filled with PDF or AVI/video files.