Well, bantios...then you don't know much about performance. When you use flaps 25 on T/O, it's because you are somehow runway limited. You need to get airborne quickly. When you find the required flaps setting, you also check that you don't exceed your climb limited weight. So your climb performance is as good as for flaps 1 T/O.
Example: Let's say for a flaps 1 T/O your runway limited weight is 70 tons, for flaps 25 on the same runway it might be 60 tons. However for the flaps 1, your climb limited weight will be higher than for flaps 25, so you have to reduce your TOW accordingly to comply with the climb requirements.