Constant lagging and graphical glitches in LAN Co-op

So me and my brother have been playing through and everything was going smoothly until we started UVHM. I started getting constant lagging and lock ups, sometimes it would last for as long as 10-15 seconds, all enemies and my brother will start just walking in whatever direction they were going for however long the lag lasts and then snap back to where they should be. (Most likely downing me since I can’t fight back while this is going on). Just last night we killed the warrior and after the cutscene I noticed the star chart from the cutscene was still visible but only for me ( http://i.imgur.com/ATiUSCD.jpg) and his character model was missing and he was just a set of guns and his class mod. ( http://i.imgur.com/Qxncyid.jpg) Even fast traveling didn’t fix his model bug.

I’m playing through steam on LAN and we didn’t have this issues until UVHM. I tried verifying my cache and still can’t figure out this issue and searching for a fix just gives me results about hamachi (Which we aren’t using this is actual local LAN in one house)

This is LAN so internet like lag shouldn’t be happening and it is also ONLY happening in UVHM, the game has been fine in the other difficulties. This is making the game unplayable.