Interpreting Xcode Time profiler

Question

I profiled my app for about 38 seconds and selected the 12 seconds that have UI problems. It looks to me like the profiler is telling me that out of the 12 seconds that I have selected, that more than 3 seconds is spent removing notification observers. Is this the correct way to interpret these results?

Answer 1

Is this the correct way to interpret these results?

Yes, that's correct -- according to your image, your app is spending a lot of time removing observers.

Answer 2

It's telling you it's spending 3 seconds out of 12 doing _CFXNotificationRemoveObservers.

Is that useful?
I would think you'd want to know why it's doing that, and whatever else it is doing as well. It's giving you a very incomplete picture.

If you simply paused it randomly (a few times) in that 12 seconds, you would be using this technique. It tells you not only what the program is doing at the time you stopped it, but you can see why by reading the stack. If it is spending any of that time doing I/O or blocking system calls, you will see that too.