Regarding this post JSONKit is fastes JSON parsing library. But after releasing iOS 6.0 these results must be updated. So was created test application for testing JSONKit and NSJSONSerialization on device(not on emulator) and winner is NSJSONSerialization. But this is not all: after seveveral days was created custom parser called OKJSONParser which is faster NSJSONSerialization on real device. For testing was used iPhone 4 with iOS Version 6.0.1 (10A523) and the results is listed bellow:
So in result: for the current moment OKJSONParser is ~30% faster in Release mode than NSJSONSerialization. For improving this results any optimizations and suggestions are welcome.