Change to lowest, put extreme frame rate.
Even with my s9 i still go low cause pubg tend to eat up battery.
In your case give it some time for ios to optimize the app.

Because of the same reason you're asking, why your phone becomes hot. Much like a pc, power is needed for the game to run smooth, more power=more battery=more heat. If you run a high end graphic on a laptop running on battery, you'll get the same result.
My suggestion to lower is to keep the battery cool and the gameplay from becoming sluggish but counter back with higher fps. This helps for you to save the battery life, while enjoying a smooth gameplay.  This game is for you to enjoy the battle, not to enjoy the graphic.

Guys, anyone play using bluetooth head/earphone in this game?

Got any audio delay?

Not sure whether its a hacker with Mighty God mode or what, but really sure I knocked that fella out with VSS inside a hut from far, but when I went in, that damn fella still well alive and he/she put lots of bullet into me. Shait!

anyway, what would be your best choice of weapon to have?

mine would be AKM and M416 (with all the attachments n suppressor)
if thats not possible, UMP with M416 (with attachments n suppressor)

its because easier to find UMP and its attachments.
vector also nice and easy to find attachments.

i dont really fancy sniping. but as game progresses, less and less player around, need to do some sniping at times.

to me, if i need to snipe, i can use M416 with single shot with suppressor and 4x or 6x.

to those who uses kar98 or AWM, whats ur second weapon? AR or SMG?
whats ur tactic like? one AR/SMG for close/medium range combat and u will snipe for long range enemies?
i cant really snipe without scope though, hence i dont prefer kar98 or AWM

For fun, nope, but for a person that aim for tournament, bare hands is our friend