The issue focused on "wasted time" as you go through a window for every 12 seconds or so. So if you set it to run at 12 seconds every 12 seconds, it will run for 12 seconds every 12 seconds. That's less than half a second per window. 
 
 With an infinite window (infinite runtime) this could be fixed by keeping the window size constant or using a run-time pause during which to wait for the window to fill up. 
 
 That said, it should be noted that this may not be how you want to think