The game runs so bad in Co-op

Why does this game run so poorly? I played it a few years ago on the Xbox 360 and it ran fine. Now on the Ps4 it is nearly unplayable. I am playing with the same person as well. It also makes the playstation party lag and useless. I have never played a game worse than this.

Never had the problems you write about. For me it runs smother and the party chat just works fine.