@superlancelot, unfortunately, DB 3 works much faster on practice. After we've changed the playback library from 3 to 4.3, our game FPS dropped down significantly, I can say from steady 60 FPS to 40 - 45. I tried to optimize a lot of DB classes, but it all help us win just some 7 - 10 FPS. So we rolled back to using 3.0 and the Flash Design Panel, because it supports many nested animations which we already had done
I'm not sure if you've already optimized the TransformUtils class, but it provided the heaviest payload for the CPU. You probably need to compare two versions of DB, with the same assets using Scout. You'll see how much more work the DB 4.x makes it to do