Sometimes the print layout takes a long time to redraw if there's complex symbology and labelling in the data being shown. When editing the non map elements like the legend, scale bar, text disclaimers, position etc there is no need to see the map.
Can the redraw be turned off or put into draft mode like in ArcMap? https://desktop.arcgis.com/en/arcmap/latest/map/working-with-arcmap/pausing-the-map-s-drawing.htm