Game crashing everytime I go downtown

So I'm pretty stumped by this issue as it's just started happening out of the blue, and I haven't added any mods that affect the world in its entirety... just mods for settlements. Anyways, any time I try traveling through any part of the downtown area, my game starts losing frame rates really fast, and then just freezes entirely. I literally have to save every thirty seconds to make it through some missions, and it's getting ridiculous. I can prance my merry way through the outer wastes all day with zero issue, but as soon as there are big buildings around it just goes kaput. I was just wondering if there have been any specific mods that have been known to cause this issue? I'll be happy to list out my current mods/load order if necessary, but I'm hoping for a miraculous easy solution.

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Thanks in advance all!