M4700 Takes ages to boot when docked and connected to an external screen

Hi, I have a Precision M4700 which i usually keep docked on a port repilcator connected to a U2713 monitor with a display port cable. When i power on my laptop whilst it is connected to the docking station, it will take ages to boot. If i take it off the docking station and power it on, it will boot to the login screen in roughly 10 seconds. Would the DDPA software be a problem or perhaps a graphics driver or the BIOS?

Thanks in advance.