The QuickBuildFactory class is a subclass of GNUAutoconf which
assumes the source is in CVS, and uses mode='update' to get incremental
updates.
The difference between a “full build” and a “quick build” is that
quick builds are generally done incrementally, starting with the tree
where the previous build was performed. That simply means that the
source-checkout step should be given a mode='update' flag, to
do the source update in-place.
In addition to that, this class sets the useProgress flag to False.
Incremental builds will (or at least the ought to) compile as few files as
necessary, so they will take an unpredictable amount of time to run. Therefore
it would be misleading to claim to predict how long the build will take.
This class is probably not of use to new projects.