With zbrush or substance you can handle a 10 million or 20 million polygone baking without fancy graphic card with zbrush as long your ram is enough to make a10k or 8000 face without any problem, on blender as long as you have a fast cpu or gpu and a lot or ram it's possible but not so easy to do it can stop baking even on a 16 go of ram computer.
baking with cycles can be very heavy for your computer... Go to your rendering options and change cpu to gpu, and make sure in your blender properties that you're using OptiX
