The time that it takes a turbo to spin up or start working in its' most efficient range is called turbo lag. Think of it as a delay in the amount of time from when you depress the gas until the engine starts to speed up...the bigger the turbo, the longer the lag. But bigger turbos make more horsepower overall...
dang man, your car has some serious turbo lag but hey, once that baby kicks in it destroyseverything on the road
Lag is a word used in many different games, and on the internet. It means that the game/website isn't working properly, and in most cases, that the FPS are low.