I was using the standard graphics card drivers shipped with the operating system - and those (as well as the older manufacturer-supplied drivers) do not support OpenGL. Ghost Master uses OpenGL for 3D rendering - and with OpenGL support missing apparently reverted to a software renderer (which explains the extremely low frame rate).
The following three steps solved it for me: 1. Got the graphics drivers from the manufacturer of my graphics card and installs them. At least with ATI and nVidia this will install a fairly decent OpenGL infrastructure on your system. Unfortunately the only "improvement" this brings about is that now the screen goes white and "ghost.exe" crashes in atioglxx.dll every time you try to launch the game (according to the posts I've read it might be that only the combination of Steam-Version of the game plus ATI card is affected by this problem...).
2. Edited the resolution settings to fit the specs of my card and monitor as described here: forums.steampowered.com/forums/showthread.php?t=895521 (honestly I am not quite sure if this step was essential for the solution, but I spent so much time on getting the game up and running that I did not feel like going back and test this as well...)
3. If this does *not* solve the issues for you, you might want to give the NoCD patch a try. It did finally fix the problem for me, and no, I won't post any links... it's sad enough that you have to revert to dodgy solutions to run a game you actually paid for