When I lock my Macbook (CTRL+Shift+Eject) the screen blacks out and the LED goes on. When I hit enter then, the LED fades out slowly and after that I can enter my password. Is the fading time reducible? I want to enter my password immediately, because I have to lock my Mac very often.
On my MBP (mid 2011) the LED turns off and the screen goes on almost instantly. By almost I mean perhaps a split second, which is hardly noticeable. To make it come on literally instantly would be impossible due to hardware limitation. In other words, your screen isn't programmed to turn on with a delay, it turns on as quickly as it possibly can after receiving the wake-up signal.
As to what your problem concerns (assuming the delayed wake-up of your monitor is the issue), you should be able to start typing your password as soon as you wake up your macbook, so that when your monitor eventually comes on, you'll already be logged on.