I've noticed DF takes up more cpu resources during the change of wallpapers.
In fact, when gaming it stutters the game.
Is there a way to give DF a lower priority?
You can enable the "Run as low priority process" option in the Settings > Advanced Settings window.
In the wallpaper window, you can also click "Wallpaper Settings" and enable the "Pause wallpaper changes while a full screen application is running" option to prevent DF from setting the wallpaper while a game is open.
Hope that helps!