UVPackmaster 2 is an efficient and fully-featured UV packing engine available for Blender. It is the most efficient UV packer out there in terms of packing on CPU but it also provides a Cuda accelerated variant of the algorithm. When running on a GPU it significantly outperforms all other packers available.
Note that UVPackmaster doesn’t only mean high performance – it also provides a lot of sophisticated features not available in other UV packers, greatly simplifying your UV packing workflow.
The engine can be used together with Blender (2.8 – 2.9) with the UVPackmaster add-on installed.
To improve your UV workflow in Blender also consider Downloading the Zen UV add-on by Sergey Tyapkin.