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.
Used to allude that the last force, problem or burden which is seemingly minor and small causes a person, system or organisation to collapse or fail
Her husband's violent act last night was the straw that broke the donkey's back and she left him