frogs are med size class, xp bonus or lack there of or a - one of it is based on two things the race group ie. large med small and then iksar and troll are tossed into their own group
then its the class, ie melee's and pure casters are at 0 bonuse then its healers are at a little bit of a - bonus then its hybrids at a little bigger - bonus.
gnomes, dwaves and halflings are the fastist at geting xp,
then wood elves dark elves high elves hafe elves humans frogs eruidts and val shar (they are the med sizes)
then its the ogres, barbs as the large races
then its the iksar and trolls who have the worse xp bonus,
also humans are considered the standered by which all others are measured so the gnomes dwaves and halflings in sony's eyes actually have a +bonus where as all others are at 0 bonus or a - bonus (realy its that there is no bonus but there is a penilty for your size or if you have regen, as to weather a iksar or troll levels faster i dont know but i do know that of all the barbs iksar are my prime choice for a race in the shaman class they have the highest wisdom decent sta and their inate ac bonus helps when your playing a non plate class, their xp penilty is not realy that big of a deal when you can grind with good friends.)