Not necessarily. It could simply be a question of scale. Being analog and molecular means that brain could be doing enormously more than any foreseeable computer. For a simple example what if every neuron is doing trillions of calculations.

(I’m not saying it is, just that it’s possible)

I think you’re merely referring to what is feasible in practice to computer with our current or near-future computers. I was referring to what is computable in principle.