[plt-scheme] What's the effect of DRPLTCM?

Hi everyone,

I'm working on a project using a lot of modules.  While I'm developing, I 
run my test cases, and they've been taking upwards of thirty seconds to 
complete.  But I've figured out that the timesink is due to module 
compilation, since if I compile all my modules using 'mzc', the total time 
drops to half a second.

Although I can do 'mzc -k' every so often in my project directory, I was 
wondering if this is a detail that DrScheme could automate for me.  I 
looked at DRPLTCM, which looked like the right thing.  But although I set 
DRPLTCM=1 before running DrScheme, I didn't see compilation of my own 
programs when I pressed Run.

Am I misunderstanding what DRPLTCM is for?