Even if I try to double-click on the lilypond icon right now, the result
I get is that the lilypond executable appears to start, and then it
seems to just sit there. Then I would use the task manager to see if
the executable ran at all, and I would find (on the "Processes" tab)
that indeed it is running. When I look at the the columns for I/O
reads, I/O writes, I/O read bytes, and I/O write bytes, I see that it
did one I/O write, with about 2.5 MB of data written. That is what I
lazily referred to by "2.5 MB".
If I invoke lilypond by the other two methods, I get the same result.