I take it you are using the 1.4.2 version of the game, VSTEP were not given any information from P&O about the dynamics of the real ship and therefore she is very sluggish. I have attached the 1.4 version POR dynamics, which I find to be much more realistic.
To install, copy the file to My Computer >> Program Files >> VSTEP >> ShipSim2008 >> Actors >> Objects >> Pride of Rotterdam and paste it there, replacing the original file.
I did send a picture of the POR bridge poster to VSTEP so hopefully we will be gettng more realistic dynamics in the future.