Looking at the Win32::IPC source, it seems that 'wait' calls the 'WaitForSingleObject' Windows API function. The MSDN documentation for that function states:
The WaitForSingleObject function checks the current state of the specified object. If the object's state is nonsignaled, the calling thread enters the wait state. It uses no processor time while waiting for the object state to become signaled or the time-out interval to elapse.