Only utilizing 50% of available cores

I’m working with about 1600 images (2.7k) and it uses exactly 50% of my 96 cores. I’m using a server rack with 96 virtual processors (meaning 96 effective threads) from two sockets, and it uses exactly 48 of them. Why is this? Am I limited to 48 threads? This would be very disappointing.

Are you able to use these threads while working with other softwares? There is either a chance that the process is not heavy enough to need all of them or your settings directly on the servers are set to reserve some power.