That is true. Bigger organisms take a much longer time to do what they want than tiny organisms due to their complexity. If Life is one big organism, I feel like it will naturally evolve a super-smart massive "brain." We haven't gotten to that yet, just a collection of minds (hive mind) that resemble this "brain." Its intelligence must very limited. If this is true, that is undoubtedly the next step for evolution, and life is still in a very primitive form.