He was being all ironical... saying that while VNC is considered slow it is better than X11... which is mostly true. Both work fairly well over a LAN but start doing WAN stuff... and it is a race to the bottom.
The idea behind NoMachine's NX protocol was all about reducing the overhead in X11... and they have been very successful with that with NX 3. For NX 4, where they refactor everything... I saw press releases over 18 months ago saying it was coming out real soon now... and it still looks like it has another 6 months to a year to go... assuming it does complete. They do periodically continue to release beta updates.