OMFG!!!! Sorry, but there is just no other way to express my disbelief. It works. It really, really works.
It just so happens that I left my game in Markarth yesterday where I was seeing horrible, horrible FPS. Normally, I'm rocking 50-60 FPS on Ultra+ (maxed all sliders, too) and Post-Process Injector, except for places like cities, and even then the worst I get is about 27 FPS - the worst. Most often in cities, I'm getting 45+ FPS.
Fast forward to Markath yesterday - my first visit - and I could not believe it, but my FPS dropped into the teens in at least two places. It was awful. I was less than happy to see this after having gotten such good performance everywhere else with the tweaks I've made.
Now today, I come across this thread (thank you Op for pointing it out) and went for it. Started my game in Markath, and immediately saw the difference. In the two worst places where I was seeing drops to 16-19 FPS, I immediately saw that I was getting 27+ FPS at the worst.
Now that alone would have made me much happier. Would prefer >30 FPS everywhere, but I can live with it in just a couple spots. Everwhere else in Markath, I was getting 45+, and normally 55-60 FPS solid. Very nice.
It gets better. Or weirder, depending on your perspective.
The more often I ran back and forth between the two "bad" spots in Markath to test the framerates, the better the FPS became, until finally I was seeing 34+ FPS at the very lowest in the absolute worst spots.
Now how can that be? I suspect were I to leave Markath and come back, I would see the same behavior - starting at around 27 FPS in the worst areas and gradually getting better until I top out around 34 FPS. Something to do with loading / caching the textures, vram, system ram, etc.
I'm sure someone much smarter than me can explain it.
Just thought I'd add to the avanlanche of "BY-THE-EIGHT-I-CAN'T-BELIEVE-HOW-GOOD-THIS-WORKS!!!" responses.

-(a very happy) RMWChaos