I noticed that I have a huge performance drop in the cities. The famous 1.4 patch made it all well and it worked fine till I installed Dawnguard and 1.7 Patch.

I am not sure is it the 1.7 patch or Dawnguard or both but my city performace is back to before 1.4 patch. At the top of the stairs in Dragonsreach its 48-50 and it was 59-60. In Riften in some parts its 40 and it used to be always 60. I am so sad. I thought those days were over.

Maybe we will need Skybooster again.

And don't say 40 FPS is good when I used to have 60 fps in that city before 1.7 and after 1.4 Patch.

same here ,not sure on the exact fps drop but when i'm in city it lags awfully,especially as i walk or run past people.doesnt happen out of the city limits or in dungeons,just cities

There's a thread about it here; http://www.gamesas.com/topic/1402076-huge-performance-loss-after-17/