Do Created Characters have issues with performance?

I'm getting mixed signals. Some people are saying:

"Avoid at all costs. It screws up the hitbox."

"No, it doesn't really matter. You'll either hit them or you won't."

"Best to just color the already made characters."

I want to create a character based on my avatar, but after hearing that there might be issues with performance, I don't really see a point in making any custom characters until I know for sure.

In addition, does giving the original characters different or joke weapons create...

Do Created Characters have issues with performance?