This is an absolute life saver.
https://steamdeckhq.com/tips-and-guides/save-storage-with-the-deck-cleaner/
Took me about five minutes (at most) to set up. Now I have it available in gaming mode and can clear my shader cache at will.
It’s one of those things that you don’t think about until suddenly it becomes an issue. On the 64 gig model it’s only just reared its head for me. The shaders don’t get deleted when you delete a game, which I have to believe Valve will fix soon, because It just eats up space and gets worse gradually over time.
So I installed this script as per the very clear instructions, added it to steam, and now I can use it whenever I need to. It just cleared the shaders for me just now and cleared half the available space on the 64 gig portion of my deck, making everything much snappier.
There’s also an option to move the shaders to the sd card. No idea how well that works but it seems like a good thing to me. Apparently the shaders recompile when you first use a game after doing this so it’s not issue in that regard either.