Really bad camera stutter when panning around

Keizer_gg10​  I've been saying for a while that the .sgr file settings don't reflect the capabilities of high-end graphics cards and can actually impede performance to a significant degree.  Why they're set up to be this way even on ultra settings is known only to the developers, but I'd guess that it's about improving performance on lower-end systems where players might still want to use ultra settings.  Or these settings were necessary when the game was released almost 12 years ago, and updating them hasn't been a priority.  In any case, you're free to adjust them to your liking.

As for imposing other settings from the old Simp4Sims file, I would try changing one set of values at a time so you can observe the effects separately.  The old file is still not safe to use overall, but the edits it contains are mostly or completely relevant now.  You can use Notepad++ to compare the two files and change whatever values you want in your newer copy.  Just be ready to revert any given change if you find it has unwanted consequences.

In case you didn't see it (or I didn't explain it well; it's been a while since I posted in this thread), it doesn't help to change all the level-of-detail values (as in, how much detail an object is rendered at for a given distance away) to match each other.  The problem, or one of them anyway, is that the game will recalculate each time an object falls into a different category of LOD distance, even if the level of detail it's supposed to use now is the same, and that itself is a major source of lag/stutter.  So that's why I suggest pushing the distances out to the max, meaning all objects will stay in the lowest-distance-away category until they're very far away, which in turn means the game doesn't try to recalculate anything until the objects are very far away.