Process that has priority above WIN32_NORMAL_PRIORITY_CLASS but below
Process that has priority above WIN32_IDLE_PRIORITY_CLASS but below
Process that performs time-critical tasks that must be executed
immediately. The threads of the process preempt the threads of normal or
idle priority class processes. An example is the Task List, which must
respond quickly when called by the user, regardless of the load on the
operating system. Use extreme care when using the high-priority class,
because a high-priority class application can use nearly all available
Process whose threads run only when the system is idle. The threads of the
process are preempted by the threads of any process running in a higher
priority class. An example is a screen saver. The idle-priority class is
inherited by child processes.
Process with no special scheduling needs.
Process that has the highest possible priority. The threads of the
process preempt the threads of all other processes, including operating
system processes performing important tasks. For example, a real-time
process that executes for more than a very brief interval can cause disk
caches not to flush or cause the mouse to be unresponsive.