Hello, I have exactly the same question. I have an animated wallpaper in the wallpaper engine, every time I do not disable the wallpaper, my fps drops slightly in games, do you know how I can fix it? I just don't understand what's wrong.
Your problem is really very easy to solve. Initially, in the wallpaper engine, you can enable disabling live wallpapers when there is any window on top of the desktop. It is also possible that in games you do not use the full-screen mode, but the window mode. When I play counter strike, I prefer to turn off all unnecessary things that I don't use while playing counter strike. I usually played with an open browser in the background, because I like to exchange items on services like https://skinsmonkey.com/ . It was due to the fact that I did not close unnecessary applications during the game that I had problems with FPS. So probably the easiest solution to the problem is to simply disable all unnecessary applications for the duration of the game. I hope I was able to help!