How big the XML stanzas can be that Openfire can deal with

Hello,everybody.

     In XEP-0065: SOCKS5 Bytestreams,they said "XMPP is designed for sending relatively small chunks of XML between network entities and is not designed for sending binary data".

     In XEP-0134: XMPP Design Guidelines,they said "The core strength of Jabber technologies is the streaming of relatively small XML fragments between presence-aware network endpoints".

     So,I wander,How big the XML stanzas can be that Openfire can deal without performance problem. 1KB? 1MB? or 10MB?

     Thanks.