I very much hope Pioneer will release a high-resolution compatible version of rekordbox 3 soon. I just upgraded from a non-Retina MacBook Pro to a Retina model, and it is incredibly painful having the text take up so much more room (so I can read far less of it) while at the same time becoming far less readable. If the program could take advantage of the actual screen resolution, I would be able to see more text, and have it be even more beautifully clear.
For now I have found a workaround that at least makes it clear, although (as you will see from the attached screen shot), it causes the waveform to render in one quarter of the space it is supposed to take up, because it draws it in half the space both vertically and horizontally. The way to do that is to modify the application definition to change the NSHighResolutionCapable value from False to True. Note that I did this on a copy of the application, and you will want to as well. The basic instructions can be found at the following link, although they say to add the two lines containing the definition of the NSHighResolutionCapable dictionary, while in the case of rekordbox, those lines already exist, and you simply need to change the False value to True: http://apple.stackexchange.com/questions/69038/open-in-low-resolution-checkbox-on-retina-macbook-pro-checked-and-disabled