Does Rundll32.exe advapi32.dll,ProcessIdleTasks really clear memory? Not really! There is a clear misconception on the net that Rundll32.exe advapi32.dll,ProcessIdleTasks clears the memory and makes the PC run faster!
More light on this from Microsoft :
The file placement optimization, which is done no more often than once every three days, is an example of a task that is carried out when the system is deemed to be idle.
System Restore and other features of Windows also attempt to defer some work until the system is deemed to be idle. There are also some done-once-after-setup work items that also operate under the Idle Task Scheduling mechanisms.
All of these “idle tasks” are controllable by a system API in advapi32.dll, ProcessIdleTasks. The APIs sole purpose is to allow benchmarks a simple way to force any pending idle tasks to be executed immediately, without having to wait a lengthy period of time.
To call ProcessIdleTasks from the command line, one use’s the syntax:
This command simply puts Windows into an idle state, enabling it to perform tasks that it wouldn’t otherwise normally do while the PC is in use; ie in short forces idle tasks to be executed; and has nothing to do with clearing memory and making the PC run faster.