I suspect that you are not the only one in this area. I too often find myself pondering about interactions with other people and realizing what I should have said. Maybe it has to do with verbal IQ versus performance IQ. I think I have a rather average verbal IQ, while my performance IQ is probably in the top 2%. https://en.wikipedia.org/wiki/Wechsler_Adult_Intelligence_Sc...

It seems that IQ scores do not dramatically change in time, meaning that improving you ability in a weak area is simply going to take a lot of practice.