It is all about processing power. metafader is a gigantic project as far as Lemur environment is concerned but it has been optimized to death - we have spent days on optimizing the code alone. However, the mixer section is based on one canvas object that processes huge amount of information in real time. Therefore, there is significant frame rate drop in Lemur. On iPad Air 1 in the mixer mode frame rate drops to 32 but all the gestures are processed correctly. On older iPads the drop is significant and some gestures like double taps may not be processed efficiently. However, when you go into the commands grid mode the mixer engine is partially shut down, which significantly improves the performance and now the gestures are processed correctly. So if you want to get the best out of this great DAW controller, use the latest iPad incarnation.