Question: Is this just a new type of optimizer?
No. By definition, toolpath optimizers begin with a CAM system-generated toolpath and modify it in hopes of making it better than it was originally. This involves attempting to detect where the tool is likely to become overloaded and then modifying the path to lessen the impact when milling in those areas. More often than not, this post processing of the toolpath consists of adding new blocks of code to insert feedrate reductions in the corners.
VoluMill, in contrast, is a completely new toolpath strategy that drives machine tools and cutting tools to their fullest capabilities. It is not based on any previously existing strategy, and therefore generates toolpaths that are inherently free from the problems of CAM system-generated toolpaths. There are no problem areas, so there are no modifications that need to be made. There is therefore absolutely no need to run a VoluMill toolpath through a post-processing optimizer. Indeed, if you own such an optimizer, please don’t use it on a VoluMill toolpath; it is unnecessary, and will almost certainly reduce VoluMill’s effectiveness.