With ART, Google ships uncompiled code through the Play Store and compiles it at install time. ART uses AOT compiling, but it is compiled on the device, meaning it has much of the information JIT has about the hardware it is running on. This, combined with a modern, complete overhaul with a focus on speed, means that ART should be a lot faster than Dalvik. The only downside is longer install times and maybe a few incompatible apps from developers who didn't take advantage of the KitKat preview. We'll be sure to give L the full benchmark treatment as part of our review.