Barrel length 'Performance' isn't all about velocity.
There is accuracy per distance, which is tied to tune, and SD/ES, and muzzle pressure(slapping the back of bullets), and then bullet stability.
There is also the potential for secondary pressure peaks, that can exceed your load pressures. When that unburned powder ignites at the muzzle(doing nothing good for you), the pressure generated by it bottles up & adds to that still in the bore. This, forcing lower pressure or less than optimum loads to relieve pressure issues.
For longer ranges, and smaller killzones, these things matter as accuracy matters.
If velocity was all that mattered, manufacturers and BR shooters would just pick a standard short barrel(like 20") for all long guns.
After all, neither need longer barrels to reach target velocities, as they could just choose ever higher capacity cartridges to recover that.
But what they need is accuracy, which ultimately drives barrel lengths, neither too short nor too long.
Factories still go shorter in barrel lengths than BR shooters.
They know that for most shooters, who buy their guns, accuracy takes a back seat to other use factors. But they don't usually go full blown crazy with that.