QGIS 3.2 Layout Map render/cache/rectangle no longer available

In previous version of QGIS when using the print composer there was an option to have the map displayed as a rectangle, cached or render. This was particularly useful when the map showed lots of information and took a long time to load/redraw. I am setting up a template to auto generate a lot of maps using an atlas but can no longer find this option and it takes quite a while to render the map, even though i don't need to see it, just want to export it. Does anyone know if this feature has been removed completely, hidden somewhere else or will be implemented back in further versions?