https://wccftech.com/wow-battle-for-azeroth-patch-8-1-dx12/

The upcoming Battle for Azeroth patch 8.1 will offer new DX12 multithreading options which will offer FPS improvements by up to 25%.

Blizzard introduced DX12 support for World of Warcraft through the Battle for Azeroth 8.0 pre-patch, but the performance gains are currently only noticeable for some due to WoW being bottlenecked by CPU’s. The upcoming optimizations are said to change that, and the new multithreading options will optimize CPU core usage.