I am playing on PC EU and ESO always worked fine. All I did the last few days was install a few more Skyrim mods, but that shouldn't be the cause. (They only add up to 23MB while I still have 76GBs free on the SSD).
Update: It seems to be an unrelated issue to ESO. A memory leak caused by the latest Windows update seems to be the cause.
Update2: I don't know how, but I fixed it. My RAM usage is down from 99% to 14%, which is normal. FPS are back to 100 in instanced areas and 60-80 in crowded places.
Edited by Ratzkifal on January 30, 2018 8:13PM This Bosmer was tortured to death. There is nothing left to be done.