Board Thread:Naruto Discussions/@comment-12509038-20140806073433/@comment-3568954-20140807020313

The reason it had bad side effects was not just because he couldn't turn it off. It was because he wasn't an Uchiha. A real Uchiha could use the sharingan with minimal chakra drain, but Kakashi isn't an Uchiha. So it drained him far more quickly than it would anyone who actually inherited the Kekkai Genkai

wrong they literally say that because he can not turn it off it constantly bogs down his chakra levels. now that it has awakened that will not happen