> First, configurePersistentStoreCoordinatorForURL::::: is in no way a hot spot.

Yes, I'm well aware of that :)

> Next, you say "+dictionaryWithDictionary: is plenty fast, but it still has to allocate an object". Are you sure about that? Have you measured it? I've found that Core Foundation class clusters can defy such expectations.

I've not measured it. But the only alternative implementation I can concoct is copy-on-write which has its own expenses, and to my knowledge is not performed anywhere in (Core) Foundation.

Anyway, the real reason I'm doing this is not the raw performance, but what is cleaner code to my eye.