Yes
I don't mind if someone is retarded, but if they are not, then generally being very slow = being very selfish, imo. They could go faster, but they don't care about the other players, so they don't. These players need to be told by the dealer to hurry up, or be kicked off the table.
I have told a few people to hurry up. One guy was waiting until the action was on him then very slowly checking his hole cards. One, and then even more slowly the second. I get the idea as to why it's good to wait until the action is one you, but the extra 10 seconds it took him to check his cards every hand was annoying. I told him so. He didn't take it that well, but he sped up.
More annoying is people who think tehy are clever by playing slow to annoy people. Annoying people is not a skill. I have been doing it my whole life without even trying.