Why does the vnc query return everything?

[sound]

Am still struggling with slow queries on my site that the slowquery log says are from the ActiveRecordIterator (4-5 seconds)  and vnc (16+ seconds) calls

on looking at these queries I see the vnc/ActiveRecordIterator topic query returns stuff like last posters  signatures, fb ids, twitter info etc etc

262 fields x 25  ?

surely it has to mean quicker results if the results are trimmed down to just essentials for the vnc feature results?

what am i missing here ?