outer focus point

Canon 50 1.4 @1.4 to say 1.8, the edges are not as sharp as the center. So if I use an outer focus point will I lose sharpness at the center of pic because the camera is trying to focus the edge. I hope this isn't a dumb question.
Thanks for any answers.

Assuming that the plane of focus is the same, I wouldn't expect to see any difference.

Your point of focus will be sharp and if any other areas are not at the same distance from that point then you won't be able to get the same sharpness as your focus point. At f/1.4 or f/1.8 you have inches to play with.

So in other words, the off center subject will be as sharp as the characteristics of the lens will allow it to be. The camera is not having a hard time because it's trying to focus thru a bad spot in the lens. Thanks for the replies.