Running CueZy the 9 pad sampler on iPod Touch 5, I experienced delay problems with samples which I had set to loop. Also some samples only partially loaded. The samples I was using were mp3.
At first I thought this might be the out of date processor of the Touch not being able to cope so I tried lower and lower quality mp3s. Even though the problem was less obvious it was still there.
HOW I SOLVED THIS: I changed the samples into AAC (128). No more looping difficulties.