I use freecad for designs that need to be specific sizes and shapes, and Blender for things that don't need to be too exact...

Even the pro systems have single threaded portions for modelling. Multi thread, multi processor is only taken advantage of in a few areas, and even then the performance improvement is not drastically different in most tasks

As long as you don't need CAD levels of precision, Blender is fine. I still need to use FreeCAD when making enclosures and assemblies but Blender works well if it's more of a decorative piece. I think they are making an actual CAD mode soon so this might be outdated!