How to add a background image in spritekit

I've been working on a spritekit game lately and I'm really close to completing it. It's my first time using the library but I'm super excited to start getting the hang of it. I seem to be getting it just fine until I encountered my problem.

I was adding a background Image into my game and I got it to work just like this:

_background =[SKSpriteNode spriteNodeWithImageNamed:@"background"];[_background setAnchorPoint:CGPointZero];[self addChild:_background];

My frame rate was staying at a very high 60 FPS but as soon as I add the background image it dips all the way to a terrible 30 FPS how could this be. There is only 3 nodes on the screen. What did I do wrong?