Processor/RAM seem to have been compromised

Recently, my GS8 has become super laggy and slow in many games. The one where this shows the most is PUBG Mobile. I used to be able to play it without any issue, and now it takes minutes to load the game, and multiple tries to join a match, and the lag when turning my character or raising my gun is very noticeable. I placed it next to my Nexus 6P to see which loads first, and the Nexus was by far faster. This tells me that all the many hours of game play I have put into this phone has finally worn out the processor/RAM.

Does anyone else concur that this is probably the issue?

If so, does it make sense to try to replace the motherboard?

*Edit* I have restored to factory settings and np change.