I have never used a computer where pressing the "Safely Remove Hardware and Eject Media"-button has resulted in an immediate response. Most other functions responds almost immediate, whereas it almost always takes a few seconds for the "Eject USB Product String" window to appear. (I'll admit, sometimes it happens fast, but that's very rarely, even on new computers.)
Is there a reason why this should be slower than other commands? Is it due to the time it takes the computer to figure out what can be removed?