I've just got the dungeon keeper download off here and find its got a bad lag and is really annoying to try and play, I've tried playing about with some of the settings but nothing, I can't seem to change the cycles on the dosbox used by gog but have done my own ok? Any advice?

Does that lag occur even in the "regular" resolution mode or only in "high resolution"? That's odd. GOG just uses the official DOSbox release from the official site.
Setting a different cycle count in the .conf file should be no problem.

try disabling sound in the *.conf file. If that speeds the game up considerably then it's the sound setup. GoG has a habit of choosing weird sound cards for their DOS games. Set everything to SoundBlaster and see if that works (might have to run install for dungeonkeeper - don't remember).