Then I'd try to use lionheart governor sio scheduler for internal and deadline for external with 512 readahead for both and leave the rest alone. Maybe turn on thermal with the recommended values. You can also undervolt a little (one step should do it).
This way you should have a good balance. If it's not to your liking try to change the the governor. As all devices act different you might have to find the right governor for you.
Btw. What happened to your warranty lol