Update: This script has been moved to my scripts repo on github.
It is not uncommon for legacy 2D drawings to be scanned and then distributed as black/white TIFF files. While these files are relatively compact, viewing them can be a PITA. The previewer on windows XP (which is what we use at work) is slow. PDF files are much easier to open.
When converting multiple files this is done in parallel using as many cores as the machine has.