John:I think I remember you saying that you had your onchange script write to a pipe, and a program running under daemontools c reads the pipe and does the work. If so wouldn't it be a lot faster if vpopmail just wrote to the pipe? I think it would be worthwhile to have --enable-onchange-pipe=/path/to/pipefile. --enable-onchange-file=/path/to/file should work too. Both should have a reasonable default.
What do you think? Rick