Game started lagging after my brother joined and now everything is now lagging

So after my brother joined, my world just started lagging, i already tried everything, at first i thought it was my xp farm so i dismanteled that and the lag is still there, i deleted things from my storage and worlds and minecraft, still nothing. So i tried to change the graphecs and it still did nothing. (Screen recording just shows me crossing a block and making me lag and me going behind it