Lightroom 5 takes longer to render an image than Lightroom 3, but if it's taking 30 seconds then either you have very very large images or a very very slow processor. On my 4-and-a-half-year-old PC it takes about 1-2 seconds for develop module to render 36 Mpixel D800 images.
Rendering 1:1 previews on import makes it faster to see 1:1 images in library module, but does not affect develop module. Develop module doesn't use previews, but after it has rendered an image, it stores a develop module rendering in the "Camera Raw Cache". If you go back to the same image in Develop (without any changes) then if the image is in the cache it should render more quickly (less than a second on my machine). I don't think there's any way of making it create those develop module renderings in advance, as you can with library module previews. You can alter the camera raw cache size in Edit menu, Preferences, File handling tab. I have mine set to 20G.
Having separate catalogs doesn't make things faster (and IMHO loses many of the benefits of Lightroom's image management; I have a single catalog for my 70,000 images). However, a 64-bit operating system with at least 8G memory definitely helps, as does a reasonably fast i5 or preferably i7 processor.