One of the chief benefits of Premiere Pro CS6 is that virtually all effects can be previewed in real time, with no need to render. The downside of that function is that, if you’re working with HD footage on a laptop or slower computer, it can be frustrating to watch stuttering playback, as the computer struggles to process all that data in realtime.
Fortunately, there’s a little menu on the playback window that allows you to determine the playback resolution. If you have a sequence that is playing slowly on your computer, try dropping the resolution to 1/2 or 1/4. It will look a little fuzzy when it’s playing, but you’ll be able to see what you’re doing, and you won’t have to deal with choppy playback. Here’s a screenshot that I’ve labeled to show you where the thing is. The 1/8 and 1/16 options are unavailable for normal HD footage, but become available for higher resolution clips (RED 4K, for example).