| But | when working on code usually only a few files are changed and need to | be recompiled/linked. And then jam's overhead becomes significant.

One trick I did regularly back in the early days of Jam was to scope it to just certain directories: my part of the code and the directories where the Main (linking) rules were. I just had an otherwise empty directory with a Jamfile that included (via SubInclude) directly the Jamfiles of the interesting subdirectories.

That way I could go to that directory for quickie rebuilds and to the root for a full scan.

I admit, it is having the developer do some of what Jam should do (figure out how extensive the code changes are), but to my mind it is no more unsettling than the developer being mindful of Jam keeping state.

Christopher