You can increase something called the UMA buffer in the bios settings on Settings which will greatly improve the performance of apps running in containers that rely on the VRAM available on the Steam Deck. This is especially the case for third-party launchers installed on the Steam Deck, such as, Battle.NET, Epic Games Store and many others.
For Windows games, this is represented by the VRAM available in games.
By default, the UMA Frame Buffer is set to 1GB, in Steam OS, this is auto-managed for standard games and doesn't make any difference when changing the value.
However, in Windows, increasing the UMA buffer from 1GB to 4GB makes a huge difference to performance as you can see in the video below showing how to set the UMA Frame buffer limit and the impact it has on Windows games.
This also makes a great difference to those Third-Party launcher apps in Steam OS as mentioned above.
There is a catch though, on the odd occasion, it can have a negative effect for some games in Steam OS such as Red Dead Redemption 2 when set to 4GB, which causes a bug in the game to cap the framerate to 30 FPS around water.
So if you are playing Red Dead Redemption 2 a lot, you will want to put the UMA buffer back to 1GB while playing.