Guide for major performance well not major performance more like performance improvements with your Fire TV Stick 4K (Optional, though recommended for maximum performance):
The first step is to get an application called Kernel Adiutor and one install-able zip called Magisk. (Magisk for some reason won't link correctly, so please consider doing a google search for Magisk) Kernel Adiutor link: https://kernel-adiutor.en.uptodown.com/android. Once downloaded and ready to go, open the Kernel Adiutor app, hover over to CPU and set the CPU Governor to performance and change the frequency to 1690 and apply on boot and lastly, packages to disable (adb shell, su, pm disable): com.amazon.device.sync, com.amazon.device.sync.sdk.internal, com.amazon.device.software.ota, com.amazon.device.software.ota.override (Both should be disabled after debloated rom is installed) and amazon.jackson19. Have fun!!!!
Debloated Rom For Fire TV Stick 4K V.1.3 (126.96.36.199), ROM for the Amazon Fire TV
ROM OS Version: 188.8.131.52 Prerooted Rom, (Nougat 7.1.2)
ROM Firmware Required: Any, As long as you're fully unlocked with TWRP recovery installed!
Version Information Debloated latest prerooted rom. Magisk is preinstalled along with Magisk Manager For Recovery and AFTV TWEAKS as modules upon boot to setup wizard. System updates will skip, be sure to disable ota updates after the intial process! Screen Mirroring is disabled so each time you click on it, it'll exit right away so it doesn't take up the memory in the background as I edited the wifi_direct file in permissions!!!
Status: Stable, FINAL until next release.
Current Stable Version: V.1.3
Stable Release Date: 2020-05-16
Last Updated 2020-05-16
Debloated Rom V1.3: Wipe /system, cache, data (only wipe data if you want to start clean. Don't wipe if data is kept with your apps and other things), and dalvik cache before restoring! Let me know if you guys see an android boot up icon upon boot and don't worry about the data, its meant to make the boot faster so it doesn't take forever along with three additional modules. Also flashing update zips is no longer required so please don't attempt to flash an update zip as it cause problems with the debloating.