On switching away from Core Data
Were this a Mac app only, Core Data would probably have been fine. But it runs on iPhones too, and that’s where performance optimization becomes so much more critical.
Using Core Data on the iPhone can slow things down dramatically, especially with large datasets for operations that need to be as cheap as possible. I’ve used Core Data on the iPhone just to stick to the ‘correct’ & well documented form - bookmarking this for when things need go faster.