Use SetPriority utility to change execution priority of a running process.

DownloadDownload SetPriority.exe (16 KB).

Here is description of the supported command line parameters:

Usage: SetPriority [process id] [new priority]

Command line parameters:

process id ID of the process to change. Enter ID as it appears in the Windows Task Manager's Processes tab page.
new priority new priority code, either of the following:
0 for "normal" priority
1 for "low"
2 for "high"

Run SetPriority.exe without parameters from the DOS command prompt to see full description of the supported parameters.

Raise priority of process #6575

SetPriority  6575  2