Hi there are two ways to resolve this >
1 >
During Import, on the right-hand side check the box 'Build Standard Size Previews'
Once the images are imported into your catalog, LR will then generate previews for each image. It does take a short while best advice is to go do something else in the meantime. Now when you are flicking between images in the loup view / full screen - it should be fast with no 'loading time' ( essentially its done all that preloading already )
2 >
For images that you already have in your Library do the following:
>> Select all the images you would like to scan through, ( I usually select the entire shoot), then in the menu bar go to 'Library > Previews > Build Standard Size Previews
That should have you sorted. UNLESS.... you are planning on zooming into most of the images to check on fine detail and sharpness. If this is the case, you will want to follow either of the two options above, but this time select 'Build 1:1 previews'
(building 1:1 Previews does take a little longer and does take up storage on your computer)
Hope that helps you out.