Closed game lagging on high end PC

my pc:
CPU = FX-6300
GPU = R9 FURY NANO driver version = 17.5.2
RAM = 8GB DDR3 1600MHz
windows 10 pro
game version = 1.3

not that high end but should be enough for this game

before all there's no other game or heavy program opened and my pc is not overheating

the game is very unstable and running at low fps less than 20 in the mech 'battles' , i also tested it in a i5 4210U and 820M laptop running linux and it ran at 60 i the same situation