I ran three three trials of three tests:

1. Without Zeus running.
2. With 15 instances of Zeus running, polling a single file.
3. With 15 instances of Zeus running with no files open.

Results:

1. 0% slowdown (baseline)
2. 9.1% slowdown
3. 5.5% slowdown

I can't explain result #3. It's probably ...

Zeus does not actually use this approach in it's polling code. Instead Zeus uses the WM_TIMER message so there is no need to call a sleep function.
I don't believe he was talking about a sleep function. When Zeus is sitting there doing nothing, waiting for input, the message-loop thread is in some ...

That makes sense. It's not a good way to do it though. This is what Mark Russinovich, who knows about such things, has to say :
Polling is undesirable because it degrades performance. A thread that polls sleeps for the polling intervals, wakes up to perform its queries, and then goes back to sleep ...

I was looking at file system activity with Process Monitor from Sysinternals. I noticed that Zeus polls the currently active file every half a second. Shouldn't it be using FindFirstChangeNotification instead?