We all know that the default Blender packing algorithm is far from being perfect. Other solutions may give better results, but either they don't integrate with Blender natively or they are written in Python so they are slow. That is the reason why the UVPackmaster add-on was created. The UVPackmaster is a new efficient UV packing solution for Blender 3D. Its main advantage is its robustness. which comes from the fact that the core of its algorithm was written in C++ and runs as a separate multi-threaded application.
UVPackmaster comes in two versions: the basic version which is available for free, but has limited functionality and the extended version which is paid, but provides full options. Both versions are available on gumroad.
You can watch the add-on presentation video here: