Why Eminem raps so fast 😳

SONG
Eminem - Rap God

LYRICS / SUBTITLES
i used to rap really fast and i don't think i was really saying much but cause i was rapping fast i used to win every battle so i figured the faster you rap the better you was
so you write all your stuff down before hand right nah nah i freestyled it
you're the only white guy that knows what it's like to be a n***a

So Ray J went straight to the radio station the very next day
"Hey, Fab, I'mma kill you"
Lyrics coming at you with supersonic speed, (JJ Fad)
Uh, summa lumma dooma lumma you assuming I'm a human
What I gotta do to get it through to you? I'm superhuman
Innovative and I'm made of rubber, so that anything you say is
Ricocheting off of me and it'll glue to you
I'm devastating more than ever demonstrating
How to give a audience a feeling like it's levitating
Never fading, and I know that haters are forever waiting
For the day that they can say I fell off, they'll be celebrating