like lightning
Extremely fast. Wow, that car just blew past me—it's moving like lightning! When I take tests, I speed through them like lightning, so I'm sure I'll be the first one done.
like lightning
or like greased lightning
If someone does something like lightning or like greased lightning they do it very quickly. I ran across that room like lightning and pushed back the curtain. He spotted the gap and was through it like greased lightning.
like lightning (or like greased lightning)
very quickly.