This benchmark illustrates the impact that const'ness has on widget build times by building a widget tree with all const-widgets and then building the same widget tree without any const'ness. Local testing with this benchmark running on a Moto G4 shows that const'ness is 13-16% faster.
I'd like to check this benchmark in because the question of how important widget const'ness is comes up every so often. With this benchmark we have up-to-date data to point people to.
