As I assisted monsieur Agracier in populating this map and many of my repainted houses are used here I can say something about it.
First 60 fps is nice and I will never get such a high fps with my graphics cards ( :'() but let me tell you the human eye won't notice the difference between 24 fps or 60 fps as movies have 24 fps and still look smooth to us. But yes 16 is low and I have the same thing especially when looking at a populated city with the horizon in the background. A well known thing(especially with LandGeom=3).
Not just this map but it even occurs on the stock 4.09 Slovakia map. Somewhere I have the explanation by the creator of the Slovakia map or objects and it has to do with the LODs (levels of detail), the amount of objects and the variety of different objects. The more of all this the less fps.
Besides Madrid I have the same fps drop when flying over Canonuk's London or Paris. To be honest I haven't seen that much maps with such a variety of houses cluttered together on a large area like London, Paris or Madrid. Not even on the stock Leningrad or Stalingrad.
About the view distance to be very low. I think you are talking about the pop up distance. Some objects pop up at closer distance 'cause they have less levels of detail originally. That's a neat technique Canonuk used to improve fps (and probably saving loading time) but therefor he had to sacrifice the pop up distance. On the Madrid map it happens to several of his created houses and his bridges.
I hope this explains a bit the fps drop.
Cheers, Uufflakke.