The primary function of acc.exe regarding model optimization is merging vertices (also known as welding). When 3D models are exported from modeling software (like Blender or 3ds Max), vertices often remain "unwelded," meaning two faces sitting next to each other share geometric space but have separate vertex definitions.
This feature takes raw GPS altitude data (which is based on an ellipsoid model of the Earth) and applies a geoid correction to determine Mean Sea Level (MSL) altitude, or corrects for pressure altitude errors in aviation logs. acc.exe