Compile, Test, Change, Compile, Test... I think there is a time limit in the debug cycle where your debugging efficiency drops dramatically.
That limit is dependent on your short term memory and how long time you can sustain interest before you get bored and start thinking about other things. I'm sure the time limit is more than ten seconds, but probably less than thirty, at least if you go more than a couple of cycles.
Programming Perl, this is usually not a problem no matter how large your program is. With some other languagues, C and C++ comes to mind, it can be a real pain, a real productivity disaster. At work, the build time for some C++ stuff became such an inconvenience that we had to introduce a system to farm out compilation jobs to idle computers.
While a cool hack, it should ideally be a non-problem.