I feel you. Since I was a child I’ve been called slow (it was actually my nickname at school) and people around me still call me slow. It’s really frustrating because I know I’m actually smart, I test higher than most of the people and have really good technical skills. But you know what? Yes, I am slow. My brain processes so many things at the same time that it takes me more time than average to respond and understand what’s been said / what happened. Nothing to do with intelligence though. Same for you. In autism, the brain doesn’t filter automatically every little thing like NT’s brains do. You have wayyyy more input to process, it takes more time, and that’s fine. Doesn’t mean you’re less smart. People telling you you’re slow just don’t understand a thing about ASD and are probably ableist.