My own bird gives the impression of having to stop and go into a slow think-it-through mode. If the brain trades sequential processing for parallelism, you could be arbitrarily smart at the cost of taking a long time.
Since it’s the connections (wiring) that takes most of the room in a human brain, suppose you instead use small cells of addressable memory, to store state. The amount of storage could be greater than a human brain.
Does intelligence require copious memory? Great reasoning skills and the ability to run hypothetical situations could be quite smart, even if he can’t learn everything needed for an advanced PhD.