You might have heard about this already:
http://www.androidheadlines.com/2013/11/android-apps-could-become-twice-as-fast-thanks-to-art-compiler-in-android-4-4-kitkat.htmlAfter my Nexus 7 (2013) got it's OTA update to 4.4, i gave ART a try and the results are promising so far. I tested An3DBenchXL and my RPG. There are the results in fps per test scenario:
An3DBench-Dalvik: 59 / 23 / 37 / 59 / 40 fps
Ab3DBench-ART: 59 / 27 / 46 / 59 / 44 fps
As you can see, the Double Dragon and the Cloth test are already @ refresh rate but all other tests benefit from ART from 10 to 25%.
RPG (city / landscape / graveyard):
Dalvik: 45 / 29 / 26
ART: 55 / 32 / 27
Again, the app benefits from 4 to 22%. One thing to keep in mind when comparing these numbers is that the Nexus 7 uses an Adreno GPU, which suffers from draw calls more than others. So the actual improvement in VM speed might be larger, it just doesn't help due to the draw call bottle neck.