By default, Windows 2000 launch programs with a normal priority state which causes most games to run slowly (smoother multi-tasking). There is 2 common ways to change an application priority (at startup or in task manager).

Going in the task manager is not pratical because you have to start your game, ALT-TAB to windows, open the task manager and change the application priority. You can also change the priority at startup with an application (like the Windows 2000 Launcher) or in a dos console. Launching an app from the dos prompt is a little bit primitive so you better stick with the launcher. Some peoples started to create batch files which could launch their games at higher priority settings (but this is a painful experience).