A few hours later, while at home, I reopened my project. To my surprise, the CPU usage was fluctuating between 82% and 92%! Tapping Play caused an immediate Out of Memory notification. I closed all applications, put the iPad in Airplane Mode, cleared memory with cMemory, powered down the iPad, and rebooted. I again reopened my project...still very high CPU usage (over 80%). I tried freezing tracks, which brought the CPU usage down to about 50% (which is still high, considering the frozen tracks); however, I still got occasional Out of Memory notifications. Oddly, though, after unfreezing the tracks, the CPU usage still hovered at around 50%.
It was then that I realized that my performance issue had begun to occur around the time the iPad's battery indicator displayed less than 40% remaining power. By the time I had given up for the night, I was at 29%. I let the iPad charge overnight to full capacity. As expected, when I reopened the project this morning, the CPU usage was 22%.
Conclusion: I suspect that iOS (most likely all versions) automatically switches to a power saving mode when the iDevice's remaining battery power falls below a predefined threshold (probably around 40%), continuing to slow down (and, in some cases, possibly shut down) additional processes as the remaining battery power decreases. I am uncertain as to whether this process/mode can be controlled or turned off by the user...so it appears that my best bet is to start a project with a fully charged iPad and occasionally check the remaining percentage. I can only hope that I won't run into this performance issue right in the middle of a bíg take!
HTH,
Mike
