Thats a placebo effect the kernel is pretty much stock. Its great he got twrp made because Ive talked to developers and they couldnt make it either. So I dont understand how. If you want better performance freeze google play services and the player will actually work way better. The fiio sucks I hate it Im so disgusted ill never buy fiio again its got about 10 dollar phone specs.
I believe twrp 3.3.1 and up would root with magisk though thats what we need.