the.com/lag

means To fall behind or respond with a noticeable delay, especially a slow drag between cause and effect.

from From an old English dialect word meaning 'last' or 'slow one' — a lagger was literally the straggler at the back of the group. By the 1800s 'lag' had become a verb for trailing behind, and the 20th century handed it to engineers and gamers, who needed a word for the stretch of nothing between an action and the system finally noticing.