A fundamental problem is that OpenCASCADE, despite being the most advanced open source CAD kernel, does kinda suck. It's single-threaded (FreeCAD has it on the

A fundamental problem is that OpenCASCADE, despite being the most advanced open source CAD kernel, does kinda suck. It's single-threaded (FreeCAD has it on the main thread so any long operation blocks the entire UI) and it's… rather buggy. Recent fun example I've encountered: doing a fillet in two places at the same time can result in either an unhelpful "resulting shape is invalid" or a crash inside OpenCASCADE, depending on the selection order (!) — https://github.com/realthunder/FreeCAD/issues/202 https://github.com/realthunder/FreeCAD/issues/202