I am creating an application that fetches data from a server (like an online address book) and uses it on the iPhone. Communication and fetching data work fine. However, problems come into play when using Core Data to store the fetched info. (NOTE: I use SQLite as type of storage) Here is my set up and classes: -- DSAccount. This is a subclass for NSObject. Holds fetched info from accounts fetched from the server (accountID, telephone, mail, etc). I use this class to display info inside a table view. -- CachedAccount. This is a subclass of NSManagedObject, for Core Data. Holds exactly the same information as the DSAccount, only that I use that for storage. Way of storing data: -- Download the info from the server and make DSAccounts for displaying the information in the table view. -- Then, for each DSAccount, I first check if an account with the same account ID already exists in the database (using predicates) and if there is not, I insert a Managed Object inside the core data database and populate its properties from the properties of the DSAccount. Then, I save. However, I am experiencing performance issues on my device (even on my computer!) while saving. Consider that I fetching approx 9000 accounts from the online database, that I must save into my local core data database at once. I feel that the way I have set up my data save store has problems. Can anyone maybe recommend me a better approach?