Computer reaction time keeps America from getting an accidental shoulder to the face as Cortana catches and cuts off her startle reaction. It also makes her deliberations about how to respond to a loving gesture go by so quickly there's no obvious delay in Cortana raising her hand to cradle the back of America's head. Theta probably spots it, though.

"North and I could pass notes through Theta, but without a subvocal mic for you, you wouldn't be able to keep up." Cortana sighs and slouches a little. If they can't win the question game, they don't have a choice. "My memories won't be a problem. I'm faster and more efficient than you are, but my neural map is still based on a human brain."