I am having almost identical issues by the sounds of it, and we have very similar hardware too (i7, 1080, 16gb ram, SSD). Even with a base game, I get these slowdowns when moving through load zones, fast travelling and generally traversing the world. Running all the usual stability mods with all the usual tweaks. Also on windows 10. The only improvement I managed to make, and it was slight, was changing uInteriorCellBuffer=3 to 16, uExteriorCellBuffer=36 to 102 and iPreloadLimit=26214400 to 262144000, and this helped marginally with the stutter between cells. If you could share your enblocal tweaks(if you are running ENB), and ini file tweaks, that would be great.