Sluggishly

Because the new trainee did things sluggishly, he was told that he'd be fired if he didn't start taking his job seriously.

The river flows sluggishly under the bridge.

The mud lay thick upon the stones, and a black mist hung over the streets; the rain fell sluggishly down, and everything felt cold and clammy to the touch.

It hung together in banks, flowing sluggishly down the slope of the land and driving reluctantly before the wind[.]

"Their survival to this day tells us Mars' mantle has evolved sluggishly over billions of years," Charalambous said. "On Earth, features like these may well have been largely erased."