For the most recent types I have flown, the most common restriction has been MTOW. In second place, say 20% it is MLW and third place at say 5%, is performance (with the exception of LCY ops, when virtually every takeoff was performance limited). However, for my current type (E190), performance has never been a restriction. To date it has just been a case of turning the wick up to lift the given payload.
PM