He must have been formidable when his mind was working at peak efficiency.

Sometimes conditions allowed the network to operate at better than rated efficiency.

"I could have it running at maximum efficiency in six hours," he said.

He waited for no negative, "The human mind works at low efficiency.

Everything was operating at peak efficiency, all systems green, but she wondered, suddenly, if it would be enough.

I loved the speed and the pressure, the feeling that we were operating at peak efficiency.

You don't want me to start functioning at peak efficiency.

As if there's a part of me that isn't functioning at full efficiency.

"I shall not be able to perform at peak efficiency."

When the Service was working at peak efficiency, there never appeared to be a need for its services.