Hello
i’d like to add a secondary Disk to my PC on which i will install Windows in order to play Games that have Kernel level Anti-cheat.
i would need to encrypt my main disk so that no access/reading of it would theoretically be possible by that Anti cheat.
but i don’t want to loose any performance by that encryption;
is it possible for it to generally be encrypted,but after choosing manjaro in Grub,then logging in, it would completely decrypt and stays that way until shutdown?
… that is the way encryption works
… that is how an encrypted system is implemented
It’s decrypted when booted in order to work.
If it is not running - it is, when viewed from the outside, gibberish because it is encrypted.
The good news is that you would never LOOSE any performance because LOOSE is an adjective that means the opposite of TIGHT. You might LOSE some performance, though.
Also, the only way to achieve what you are requesting would be for the entire filesystem to be decrypted at startup and then encrypted again at shutdown. Do you know how long that would take each time?
So the Anti-Cheat Software should be able to access a Linux Filesystem, which Windows doesn’t support? Doesn’t compute… Just don’t install drivers for Linux Filesystems on Windows. 
i’ve read many threads about it and what you say is mentioned,
but also the the fact that theoretically it would be possible.
whatever that means or is supposed to mean