I'm curious about what, if anything, can be done to avoid the large FPS drops that many people see when looking certain directions, in certain areas of Markarth/Solitude/Riften. I always get 35-50 FPS, but cities take me down to 20-28. Any ideas on what could cause this, and how to increase city FPS? I've tried turning down shadows, turning off a mod that added more NPCs to cities, turning off AA, and optimizing textures/bsa, with no luck.

My hardware: i5-3470, HD 7870@1.1GHz, and 12GB RAM. As for graphics mods/settings - I'm running 2K textures on everything, realistic lighting overhaul, but no ENB, at 1080p with 4x transparency AA.

Yes, stop looking at places that have a high concentration of NPCs, those are what's dropping the frame rates.

Most people clamp their frame rates at 37 to 40 so the inevitable drops in the 20's are not noticeable, if you turn off your FPS display.

In cities, your performance is CPU limited. The computation related tasks such as controlling the behaviour of the NPCs, the various items and shops, and quest related stuff - basically everything that makes Skyrim the game it is - are all CPU tasks.

They are somewhat complex and tax even the most powerful CPUs to the limit. Add to this the fact that Skyrim is extremely poorly optimised.

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I would disable AA completely, and setting Mipmap Detail Level: High Quality (if you use any overhaul lightning mods, or any high resolution texture mods on Ati video cards)

And that not works, try to disable realistic lighting overhaul and see your frame rates on cities.

(That way tou can see how far you rig can go..!!!!)