How to Alter a Program's Base Priority at a Command Prompt

This article describes how to use the START command to alter a program's base priority level at a command prompt.

By default, the Windows NT Thread Scheduler service assigns processor time to a thread according to the priority level that is coded in the program. You can alter a program's priority by using the START command and specifying a priority level. The available priority levels are: Low (idle), Normal, High, and Realtime. When you run a program with the START command, the specified priority applies to the primary thread. Note that the program can call subsequent threads at its internally coded priority level. Running a program with Realtime priority may disrupt normal system operation and result in slow mouse response. For most situations, there is no need to run programs at anything other than the internally coded normal priority.

To run a program and specify its base priority at a command prompt, use the following syntax:

start /<priority> <program>

The following sample steps describe how to run Notepad with Realtime priority:

1. At a command prompt, type the following line, and then press ENTER:
   
   start /realtime notepad.exe
2. To verify the priority level, press CTRL+ALT+DELETE to open the Windows NT Security dialog box.
3. Click Task Manager.
4. Click the Processes tab.
5. On the View menu, click Select Columns, click to select the Base Priority check box, and then click OK.
6. In the list of processes, locate Notepad.exe and confirm its base priority level.