Higher amps controller>higher torque>lower top

Hey guys. Used to ride with 1500w controller with some extra solder on the shunt, which increased it approx to 50 amps peaks. Now with a new 3000w 80 amps controller, i did notice great improvement in torque although isnt that smooth. But. I lost about 15 kmh on top. Used to get 85kmh, now 71 is max. Is there any logic in the occurrence? My motor rated 2000w, and i know that i push it hard ( a lot, hehe, also considering an Israeli weather 38-42c daily, my motor going crazy hot).
I know that i loose performance to heat, but that much? I mean the logic tells that at least at 1st try when the motor is cold i should reach the same tops and then loose the performance when the motor is super hot.
I've ordered 3k rated motor, hoping it could handle it better and get my tops back?

At a guess, without details of your wattmeter readings before and after, your battery is sagging in voltage more because of the higher current, so the motor isn't spinning as fast.

Probably you need a bigger/better battery to go with the controller's demands on it.

Thats right i do get more sagging, and it make sense. But. The sags are only at the beginning, when the torque is at its fullest. On top speeds it stabilize back to normal sags (3-4 v)..

The key thing here is it isn't so smooth. You are running it in the wrong order motor wires. That's why its not fast.