She spoke at light speed and I understood nothing...?

[SunMoon]

Saying that someone speaks at light speed, does it make sense?

I used to say it for explaining that I was not able to understand the phone number left on my voice mail because she spoke at light speed.

???

[Anglika]

Usually we would say with the speed of lightning.

Either term makes sense as decribing something happening extremely quickly.

[jlinger]

or ... "at the speed of light" - that is, at the fastest possible speed, according to Einstein, I think?