Pit-Stops are between 2 seconds and 2.5, the best ones are anyway. As time has progressed they have gone quicker, in the past they were longer, you had to refuel in previous years, and tire changes in general were longer. In this day and age a pit-stop usually takes longer if the front wing needs replacing. But a standard pit-stop around 2.5 seconds, may seem like a rookie mistake but the pressure is intense.
Last yeah in Bahrain it happened to Kimi and he broke his mechanics leg.