iphone - CALayer - Shadow causes a performance hit?

Question

So I am doing some custom animations on my navigationcontroller and the way it pushes and pops the viewControllers.

Everything runs smooth. As soon as I add the following code (In a subclass of UINavigationController), I face a huge performance hit. After adding a shadow all animations become very laggy. Is this expected or am I doing something wrong in the code?

// This code gets called once during NavigationController initialization.
[self.view setClipsToBounds:NO];
[self.view.layer setCornerRadius:5];
[self.view.layer setShadowOffset:CGSizeMake(0, 20)];
[self.view.layer setShadowColor:[[UIColor yellowColor] CGColor]];
[self.view.layer setShadowRadius:20.0];
[self.view.layer setShadowOpacity:1];

EDIT:

Changed my shadow radius to 1 and it's still slow

Answer 1

self.view.layer.shouldRasterize = YES;
self.view.layer.rasterizationScale = UIScreen.mainScreen.scale;

I was recently having some issues with slow CALayer shadows, and that simple line of code fixed up everything for me!