Yes, even with the Unlimited memory option in THUGPro, there really still is a limit. Each CAP will crash after a certain amount of pieces have been used. I can attest to this first hand, for the most recent CAP I have been working on is unplayable due to me using too many pieces. I don't think there is a hard or known exact number of pieces. But it's definitely a thing.
What I have been doing is deleting pieces from my CAP until it's playable again and then trying to determine what is the culprit for causing it to crash. My CAP won't work without completely redoing it based on design and layout, so I have scrapped the one I was working on and have gone back to the drawing board.