The general consensus is that the most heavily-tested subjects on Step 2-CK are:
1. Internal Medicine (Number one by far), with 2-4 being Peds, OB/GYN and Psych, though there is no clear order here. Basically, it would be wise to focus on more primary care type suff, that is useful for most all Physicians, regardless of specialty. With that in mind, if you've made it this far, you should have fairly accurate judgement regarding which topics/concepts will be more high-yield in general, in case you're short on time. Good luck!