I don't know what you're going to accomplish but...
Go to start...run...type in cmd and hit enter. Then type
start X:\address of the game\filename.exe /high
replace X with the drive the folder of the game is located on, then the folder the game is in, then the actual exe you use to open the game, followed by /high
You said you needed an explanation
I don't know what it's going to do though