In my experience, Aperture and Lightroom are slow when it comes to different things. Lightroom often appears quicker, but when I tried it last time, it would often take a long time until the pixelated preview is replaced by a rendered version of the image when zooming in and using the loupe. Aperture renders everything immediately -- which shows more readily.
In the end, it's a matter of math: my D80 RAW files measure about 8~10 MB/image while the D7000 produces ~19 MB RAW files. It's not uncommon for me to have about 50-100 images per project. That's 500~2000 MB of data per project which needs to be stored and processed. Just reading this much data with modern harddrives (especially on notebooks) takes quite a while. This means, Apple and Adobe have to think hard how to conceal this load and processing time.
Instead of giving you a recommendation on a specific app, I suggest you try both apps. The UI philosophies are very different. Personally, I find Adobe's decision to structure Lightroom in modules very constricting and against my grain. Aperture's more free flowing UI feels a lot more natural. Plus, I very much prefer Aperture's file management.
YMMV.