The Yield function is obsolete. This function is provided only for compatibility with 16-bit versions of Windows. In the Win32-based application programming interface (API), this function does nothing.
Threads that contain windows should use the DispatchMessage, PeekMessage, or TranslateMessage functions. The message-loop functions handle message synchronization properly and yield at the appropriate times.
Threads that do not contain windows should use the Sleep function with a sleep time of zero milliseconds to give up the remainder of their current time slice.
Threads that create a process can use WaitForInputIdle to wait until the new process has finished its initialization.
Processes and Threads Overview, Process and Thread Functions, DispatchMessage, PeekMessage, Sleep, TranslateMessage, WaitForInputIdle