I would recommend upgrading the iPad. Here's my situation:
I have original iPad mini (same internal hardware as iPad 2) and can only run a few audio tracks, delay, reverb, Microsonic and one Micrologue before the CPU load meter hits 100% and it starts to crack up. I had the same problem with audio going out of sync and it happened with various interfaces.
Now I also have iPad Air, and the difference is AMAZING! I am running 48 tracks in my current project: 24 midi tracks including Micrologue, Microsonic and other apps like Alchemy, Magellan, Sampletank and Steppolyarp; and 24 tracks audio, with many overlapping audio clips, fade in/out curves, inter app audio send effects like Virsyn Audioreverb and insert effects like Harmony Voice (with multi harmonies controlled by Cubasis midi track). Also running some per-track EQs, compressors and delay, and Cubasis reverb in there too. CPU meter hovers around 50%. Of course not all tracks are audibly active simultaneously throughout the project, but mostly there's a lot going on at once! A few things which help to smooth the way: force close other apps; turn on Airplane Mode; hard reset your device regularly; leave a couple of bars blank before the first event in the project (this really helped to avoid playback glitches on the iPad mini).
So it is all possible, and I'm anxious to see how the automation update will perform - bring on version 1.8!
Search online for various benchmark results comparing the Air to older iPads - reports of 3 to 5 times better overall performance sound like hype, but based on my experiences, I would believe it.
Anyway the main point is: UPGRADE TO IPAD AIR (or at least Mini Retina, which is almost as powerful...)