Rendering cached images super slow?

Hi,

So I have been trying to create a small graph, aka 55 images put into a WKInterfaceImage, so imagine group with a 3 pixel high image with width of the container, where there is different positions. Now take 20 rows of those WKInterfaceImage, and then created a small NSTimer that would shift the image of those 20 rows. In the simulator it runs very smoothly, no problems, I can easily create a graph this way. But in the device, it is super slow, not usable at all, like if WKInterfaceImage cache is completely broken.

I assume the problem is that the images are not cached correctly on the device, so when I each second switch the image with setImageNamed, it just doesn't work on the watch?

This is taken from documentation so I am still mystified to what the problem could be:

https://developer.apple.com/library/ios/documentation/General/Conceptual/WatchKitProgrammingGuide/Images.html

Use the

setImageNamed:

or

setBackgroundImageNamed:

methods to assign an image that is already in the WatchKit app bundle or that is currently in the on-device cache. Specifying images by name is preferred because only the name string is transferred to Apple Watch, which takes less time and uses less power than sending the entire image. WatchKit searches your WatchKit app bundle for an image file with the name you specified. If it does not find an image file in the bundle, it searches the device-side image caches for an image with the given name.

What is even wierder is that UIPicker works just fine... when I roll the digital crown it has no problem switching between 300 images, but when in code I switch the images... it lags?!?