Perhaps some have noticed, if load save game somewhere in a high load place (some town for example), FPS will be fine. But worth making a fastravel wherever and back to load place, FPS down on 6-10 FPS from 60. Moreover, if you moved from the open world, where you moved from, will not be tree LODs and if use "tfc" and move camera to this place, may see the grass on the terrain LOD.
Based on the foregoing, I call the gaming community, and in particular skse plugins developers (and anyone who knows how to work with memory), pay attention to it. Possible solution to this problem (no unloading cells and processing cached cells) improve performance and stable game.