There are no exact hardware requirements and it also depends on Mac or PC.
A Mac M1 will run 2-3 time as fast as a PC. The baseline $699 Mac Mini with only 8GB RAM will be much faster than a $4000 gaming PC with 64GB RAM.
For a PC, I would say 16GB minimum but more is preferable. For processors, probably i7 or better. A good dedicated GPU is needed too. Face detection all runs on the GPU.
For Mac, any M1 will be super fast. There really isn’t much speed difference in any of the M1 machines. However, with more RAM, it will use less swap disk so it will run a little faster and not wear out the SSD as fast because swap disk writes directly to the SSD. So for an M1, I would still suggest 16GB or higher.