OpenCAMLib is an open source CAM library created by Anders Wallin. It offers high quality waterline generation and drop cutter sampling algorithms. For drop cutter algorithms it's more reliable than Bullet Physics (Blender's built-in collision detection library) and offers better performance (up to 30 times faster than regular algorithm on 24-core machine).
To use OpenCAMLib with BlenderCAM, it needs to be built from source and installed inside Python disribution bundled with Blender
To use OpenCAMLib waterlines, select "Show experimental features" in Blender User Preferences / Addons / CAM - gcode generation tools. Then select Waterline strategy and "Use OpenCAMLib". The current version lacks dialog for waterline resolution and automatic determination of cutter length, those can be adjusted in scripts/addons/cam/opencamlib/opencamlib.py.
For "parallel" strategy and other drop cutter sampling operations select both "Use exact mode" and "Use OpenCAMLib".