I only installed mods a few days ago, as you'll see in my topic on multiple marriages and such, chrisowens, the creator of the SFCRevamp mod helped me with the process of installation. So it's been a somewhat pre-mod occurrence but I'm sure it's likely due to the influx of materials and subordinates I have, I usually end up collecting the best ones I find like candy and forget there's like 15 unique's and and so I end up restarting. It's also likely a performance issue on my part, as I'm using an acer laptop. Not a high end desktop or any of the latest software. I do wanna get a decent rig set up one day and hopefully play this after civil war without waiting 5-10 seconds per day skip. But as I said, it's likely performance/rendering issues on my end, not the mods or the game in and of itself.
(Edit) It was the Polygamous marriage topic, and I installed the mod a week ago. And the delays after each full day skip near mid-game or 12-15 hours gameplay content have been happening prior to that.