Speed demon American noun informal
Used to refer to someone or something moves or works at very high speed
He used to be an awful speed demon. Other athletes were afraid of his speed.
My new laptop earns its keep as it is a real speed demon compared to my old one.
Very quickly
Very fast.
Very quick
Extremely fast as if having been abruptly startled or shocked
The origin of this expression is not clear.
To say the same thing repeatedly
Ok, I get it! You sound like a broken record, seriously!