you won't run it on ultra with a 560ti. What are the temps looking like on your GPU and CPU during these moments, use evga precision or msi afterburner to graph gpu temps and or speedfan for cpu temps. Suspicision is the card or cpu is overheating and throttling.
Turn on VSync and set the video settings to AUTO. It is pretty good at setting what it needs to be. Start with that. A 560Ti won't be able to run multiplayer on Ultra. Most likely a combo of High and medium. My guess is High details with some items set to medium to get 60FPS. It will also depend on your screen resolution.
I actually found on another forum, they were saying one gig video memory was not enough for ultra settings. So I turned textures down to high, and turned AA down to 2x and now the game runs pretty perfect. Thanks for the comments anyways, hopefully this helps other people.
My single 560 Non TI gets 45 FPS on Ultra, 1920x1080, 2xAA. I also get annoying lag spikes after about 5 Mins. It dosent happen in single player. Out of VRAM? Out of RAM?