iOS app freezes when changing CLLocationManager accuracy, returning from background state

I'm using CLLocationManager instance, even while running in background.

To save de开发者_运维技巧vice power, I interchange between kCLLocationAccuracyThreeKilometers and kCLLocationAccuracyBest

When I restore app from running background, CLLocationManager instance activates kCLLocationAccuracyBest, if it's not using this accuracy.

However, there seems to be some kind of freezing for about 2~3 seconds, not responding to user interaction.

If I'm not wrong in analysis, changing the accuracy of CLLocationManager instance seems to be the main cause.

Can anyone explain what limitations I should be aware of, when changing CLLocationManager accuracies?

And, also do anyone have some kind of solution to this issue?