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I use a lot of print statements for various diagnostic reasons while developing. Should I go and comment them all out for a final compiled product that is performance critical?

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Like with every performance question: profile it.

"Should I go and comment them all out for a final compiled product" nope. Depending on how many there, that would take a really long time, and in any case would be a waste of your time.

Instead, using a logging framework, that lets you set log levels by class/subsystem/etc. In prod, you can have all higher log levels (e.g. error, warn) be logged, but not lower ones (like info and verbose).

Also more generally, learn to use a debugger, and you'll notice you'll have much less need for copious log statements.

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Perhaps I should not have used the word "diagnostic" as I did not mean to give the impression that I use the "print" statement for debugging. Of course for the purpose of dubugging I use xcode's built in debugger. I use the print statement to report certain milestones as my app launches. In any case my hunch is that any print statements are ignored when producing a binary but I'm not 100% sure. I do take your point about profiling and I will try to do that.

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print(...) is (primarily) for sending stuff to standard output. This is absolutely necessary even in release builds for command line tools. Nothing will optimize it away. (Even a GUI application can be launched in such a way that the standard output is displayed.)

That is why @AlexanderM advised you to look into using a logging library instead for that sort of thing.

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