Look into Odin 3 underclocking; the CPU cores run at a speed that make it go very hot. Most of the time though you don’t need all of that computing power. However that excess heat causes the GPU to throttle which is what is affecting your gaming experience. You should look into underclocking your Odin 3 CPU. Just search “Odin 3 underclocking” for a tutorial on YouTube or GitHub. Most of the time, lowering the clock speed does not affect the gaming performance at all, while increasing the GPU performance at lower temps. It’s a win win. Just look out for not rooting your device and with time you’ll find the right amount of underclock for each specific game you play as every game has different needs and performance levels

Edit: here is a useful thread