Hey,
Thanks for the report, sorry to hear you've ran into this,
New Port in Act IV is pretty heavy and has a lot of geometry going on - I've tried my best to optimise it but it's still the heaviest scene by far due to having a lot of city meshes going on in the city, or props on the sites, or trains moving around, along with the terrains themselves.
In the settings menu there are options to reduce the draw-distance of the camera OR you can look at reducing the graphics quality, can you try reducing one of those down and seeing if it helps? Part of why I ask that is I've only tested / had friends test with GPUs present, and don't have anything without a GPU to hand
- Peter