JSon is basically a format of plain text. As such it can't be faster than the best plain text format. (It could be faster than a poorly chosen plain text format) JSon is used because it makes encoding and decoding easier and is fairly human readable for many types of data, esp complex ones.
If you are looking for an alternative to which you are using now, perhaps you could give some more details of the data you are sending and we can suggest alternatives.
