This link shows us ways to do this through unmanaged code.
You could use the process class to access a process and then set the priority for e.g. something like
Dim myprocess As New System.Diagnostics.Process()
myprocess.StartInfo.FileName = "C:\myprogram.exe"
myprocess.Start()
myprocess.PriorityClass = ProcessPriorityClass.High
Environment.Exit(1)