Returned to Cyrodiil yesterday, after a week pause, since the lag was horrible, the worst ever, as I've experienced it, down to 17 FPS in keep battles, with a kind of lag that made the game unplayable. Prime time yesterday was great however. Large keep battles with FPS usually between 20 and 30, with a kind of lag that was often unnoticeable because it was usually in sync with all the tremors, shaking and firework during battle. This was on a relatively good computer (4.6 ghz cpu) and wifi connection, with graphics on ultra, and two addons.
Maybe improvements were caused primarily by me playing with a brand new gaming mouse. Anyway, here in the Norwegian mountains, Cyrodiil is okay now. Please don't mess it up during next maintenance.