In Minecraft, for example, I only have 23fps (with shader). The CPU and GPU are not really stressed. Temperatures are also in the normal range.
CPU: i5-9600K
GPU: RTX 2060
Minecraft is badly programmed do you at least use optifine?
How full is your ram Shaders can use a lot of RAM, so you may need to add more RAM to the installation. You can see the load using the F3 key.
You can allocate more RAM like this: https://www.wikihow.com/Allocate-More-RAM-to-Minecraft
(There under "Launcher version 2.0.X", the installation of Java should not be necessary)
As far as I know you can only install shaders via OF.
Hm bruh
Install OptifineHD, that should help.
And give the game more memory.
I allocated 8GB of RAM to the game. It shouldn't be that
Optifine is installed. The game has 8GB of RAM.