Chapter 5Performance Tuning

Brent Simmons, creator of NetNewsWire, once shared a story about a user who filed a bug report about the poor startup performance of NetNewsWire. Upon discussion with that user, he discovered that the user had more than 900,000 unread RSS feeds! The lesson I took away from that story is to expect my users to put thousands of times as much data into my applications as I’d ever consider reasonable.

While we’re working with Core Data, we need to consider the performance impacts of our design. We might test with a couple of dozen recipes and expect our users to load a couple hundred recipes into our application and test with those expectations. However, our users can’t read our intentions or expectations. As soon as ...

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