When using a UIKit object you often run into one of the two problems.
1. Cocos2d freezing during core-animation or UIKit Scrolling.
2. Bounce and kinetic scrolling not working in UIkit Objects.
If you use the threaded director both problems go away,
[Director setDirectorType:CCDirectorTypeThreadMainLoop]; //For replacing Fast Director
[Director setDirectorType:CCDirectorTypeNSTime]; //For replacing Default Director
(it has to be the first call to the director).