Best answer as chosen by user fosterpapillon: I would start
I would start with clearing the PRAM, and then if that doesn't do it, disconnect all USB devices except your mouse and keyboard. If things improve, then you get to add devices back one at a time, rebooting each time a device is added, until you figure out which one is causing the delay. It will be exceedingly tedious and boring, but it's also the only way you're going to figure out what device is the problem. And you have to figure that it might take you, say an hour, to do this. Right now it takes about 2 minutes for you to go from power on to a usable system. So assuming you do that once a day, after a couple of months you will have "wasted" more time than it would have taken you to sort this problem right now. You may also get lucky and the first device you connect is the problem.