[NWN] Variable EXP's by class?

[Maxwell's Demon]

Since purchasing NWN two weeks ago I have run through the prelude and the first two sections of chapter one with several different characters. I noticed that my fighter gains far fewer exp per encounter than my wizard even though their levels are equal.
Anyone know why this might be? Or is this just a bug which has yet to be foxed?

 

[Lazybones]

There is a known bug/feature where summoning monsters affects the experience that you gain for encounters. The game also gives more, not less, experience to higher level characters for facing the same challenges. Personally I hate it and always use the XP system in the Hard Core Ruleset (HCR), which is based upon the tables in the DMG (although since there is more combat in the average NWN session, I multiple all monster Xp by .25).