This is only one possibility. There isn't enough info to make this claim, but I like to post it just the same.
I might be the case that your son in gifted and this isn't being properly channeled.
Gifted children tend to learn through experimentation, rather than copying behavior. If this is the case, you should notice that the hitting is not fighting or a power struggle. Instead he experimenting in invoking reactions.
There could be many other reasons, but this might be the case here, as you mentioning him being bored by the activities of his peers. This is not the behavior people typically think of when mentioning gifted, but it is typical at this age nonetheless.
You should also see some of the other characteristics of being gifted. At 3 you may find your son already start to read a little, knows detailed information about subjects that interest him (like a all kind of dinosaur names, car brands, etc) or can learn a second language from watching cartoons.
If think this might be the case, seek help of a support group.