Single player unplayable frame rates while multiplayer has no issues

I can run full Ultra settings on multiplayer and still have stable FPS but single player can’t even handle full low settings. It has been this way since I bought the game way back during the first few days it was out. Recently I’ve been using an Offline mode mod so the game is playable. (since it’s not hosting a server at the same time at least that’s how it was explained to me.) However after each update I now have to wait till that mod is updated to even play the game. Is there something I can do on my end or is this just how the game is?

Reason why I don’t just play multiplayer is I don’t want people stealing all my stuff when I’m gone which just keeps happening every time I try. It’s like Roaches they just find a way in and I don’t know how. Server wipes, losing progress is never fun, at least for me. I’m socially awful and would rather go full hermit in singleplayer/ co-op with the odd person. The whole clan thing is nice but I never really fit into that whole scene.

As a workaround download SteamCMD.exe and install it. Then follow this guide:

This way you’re using a dedicated server. Start a singleplayer game and it will automatically connect to your dedicated server instead of an online server.

Thank you I will definitely look into this!