Multi-threading is not a good analogy. If you think of the conscious brain as a hyper-visor which is switching execution context between multiple virtual machin

Multi-threading is not a good analogy. If you think of the conscious brain as a hyper-visor which is switching execution context between multiple virtual machines, the analogy sticks slightly better. Running too many VMs (on what seems like a single core processor) will slow things down and is akin to context-switching between "neural activities". It's a whole host of things that the processor needs to setup before executing instructions in a sandbox. Switching between threads is cheap and the conscious brain does it all the time, even when you're focused on a single task. But it's all so relative and comparing it to a "computer" and claiming it's not efficient is not fair. In fact, I'd argue that the human brain is a lot more efficient at handling tasks because not only is it executing instructions, it's constantly learning and programming the next set of instructions.