Definitely your CPU. PUBG has the FX-6300 as the minimum requirement which translates into "Use this if you want the game to kinda run." But before you do that, try reading this:
http://www.pcgamer.com/best-pubg-settings/
I found it and the link before from a quick Google search on PUBG's system requirements.
http://www.pcgamer.com/pubg-system-requirements/