I have heard by now a number of times that Jettison is slower than Jackson when it comes to handling large JSON sequences.
To be honest, I am not sure what this argument is about. Perhaps because I do not understand JSON ? I would rather see statements like : Jackson is a popular JSON processor which can let users create correct JSON sequences without users having to introduce JAXB dependencies. This is something I can get.
The argument about the performance sounds like a red-herring to me. Are you writing a service which returns a 7OK JSON sequence ? Is it the sign you may need to rethink the way your service has been designed ? IMHO JSON is not the means to pass around huge sequences, it is the format which has been designed to help users streamline the development of client-facing Web frontends, at least this is my understanding.
So if you need to deal with large chunks of data then may be you may want to return a JSON-formatted Atom feed, something that Abdera supports, with links pointing back to the next chunks of data. Or just use XML for a similar purpose ?
Having said all this, I will be happy to see Jettison supporting streaming eventually. Hope it will happen soon. The most important thing though is that it will now more likely to produce correct JSON sequences which is what users really want.