releng-tool will generate statistics for a build (such as the duration it takes to build a specific package) and place this information in the output directory. If an environment has Matplotlib installed, PDF-format statistics may be generated for a more visual inspection of this information.
If a user does not want PDF statistics to be created, the quirk
releng.stats.no_pdf can be used:
releng-tool --quirk releng.stats.no_pdf