Fastest practical language

I know this is subjective so there is no one answer but I would like to hear your opinions anyway.

Which language has the fastest performance for most tasks while still being practical to write in?

(1) Languages do not have speeds.
I was under the impression that a given language feature could prevent optimizing compilers from being as aggressive as it could be. Then again, I don't know much on this subject, so I don't know, for example, what such a feature might be, and why it would be difficult to optimize.