Blizzard has made rendering changes to World of Warcraft as this MMORPG does no longer support the DX9 API. They added full support for DirectX 12, meaning that players can now choose between DX11 and DX12.
While it appears that the team has not implemented any exclusive DX12 features or improvements, it’s a pretty cool addition. Also, do note that the DX12 mode is only available right now for AMD users. NVIDIA users can enable it, however performance takes a noticeable hit (so for now stick with DX11).
Blizzard has also removed the fullscreen exclusive mode that it supported before. As such, gamers can now choose between Windowed and Fullscreen Windowed. In addition, there are new controls for adjusting the graphics quality. Instead of choosing between "Low", "Medium" and "High", the options can now be set in a range between one and ten.
DirectX API Support
Previously, users could choose between DirectX 9 or DX 11. Now, the DX 9 API option is gone and DX 12 is added. Because the servers will be down for the next several hours, I can't offer any insight into performance changes at this time.
Graphical Options
World of Warcraft ditches the old "low, medium, high, etc." approach and simply uses a slider from 1 to 10 as the presets. This hasn't changed. What has changed is the graphics options tied to each preset. Previously, all individual settings maxed out at level 8, with 9 and 10 adding extended distances. Now, those settings max out at 10. Assuming all else is equal and you're still on DX 11, the level 10 preset should offer the same performance as before, but the presets beneath it should offer better performance than they did before solely due to the attached graphics options being lower than they previously were at the same preset.
If you've become accustomed to playing on a certain graphical preset, you may want to experiment with raising it 1-2 levels after the servers go live. Otherwise, some of your settings have been reduced.
Exclusive Fullscreen Mode is Gone
Previous options were Windowed, Fullscreen Windowed (AKA, Borderless Window), and Exclusive Fullscreen. The last option is gone. If you were previously running in Fullscreen Exclusive mode, upon your first run after the patch you'll default to Windowed mode.
21:9 Users
Cinematics in the opening menu were previously set to 4:3 to 16:9 in a pillar-boxed mode. They now support 21:9 to varying degrees. The vanilla cinematic has a thing pillar-boxing on a 21:9 display, while the Legion and BFA cinematics are full 21:9 by default. The others cinematics fall within either of those categories. Will be curious to see if the in-game cutscenes have been adapted as well.