Hi Nik,
I see at least 2 things in your mod list i wouldn’t have.
1) Frozen Harbors by Onealex, is made for his modpack not stock GWX
2) German U-Boat Compilation 2 by Wise, is unfinished mod hence prone to big troubles
Last, my GWX_Enhancements can bring perf hits if your computer is line edge.
Other than that, try to deactivate each mod one to one and see who is the culprit!
