Hello,
I also have this FPS problem sometimes. I confirm that it is related to 1 or more addons. This no longer happens when I disable addons. I have a big configuration, I have no problem on other AAA or MMORPG games. Hard to say which one. I know that there is a problem seen on Reddit with the module of Shinni (Node unknown for harvestmap) which made the game crash. Otherwise I found that the addons which calculated timers for various things took too many resources and was one of the main causes, like BarSteward which I use to display various things (there were calculations for end of traits, reloading and other stuff). Disabling the timers solved this. Anyway for this addon. This problem still happens at times, a list of common addons could be a start.
https://www.reddit.com/r/elderscroll...ew_zone_galen/