Performance of buffer based functionality (JSON, AES, serialize())

Hi, Completely different topic :) I've been looking a bit into performance around json encoding, hashing+encryption (aes) and serialize()/unserialize(). Data that is marshaled and often transmitted over the wire. I know there have been some high-end apps that have benefited from some custom serializers, etc... (typically platform dependent). I wonder if people here think improvements in these areas would move the needle for the majority of mainstream apps or not. Thanks, Andi