[dheavy]

Actually, "esprit d'escalier" is indeed used in French, though less commonly, especially outside of literary contexts. It refers specifically to the inability to come up with a timely response or comeback (and the frustration of finding the "perfect" reply when the conversation is already over). On the other hand, "présence d'esprit" has a broader usage in everyday language. It can mean having a quick and witty response (the opposite of "esprit d'escalier"), or more broadly, the sudden ability to judge and react appropriately in a situation.

edit: typo