I use a free program for culling called faststone image viewer. It displays the small jpg that is attached to the raw file so there is no delay at all loading images. Also if you click and hold the mouse it zooms to 100% again with no delay , and back to full screen once you release the mouse. I use it to scroll through and tag the keepers , then select the tagged files and put them in their own folder. This way i dont have to import 3000 photos into lightroom which takes forever.