Great to see that you won't allow yourself to be kept down! :)
I must say first, that Aquh is teaching me that I, for one, am probably being way, way too fanatic with polygon count reduction, because I get no lag whatsoever in this age, despite the massive amount of geometry detail on some parts (this is with a NVidia GeForce 8800 GTS).
A few tiny details, which I noticed, at a cursory glance and which may or may not show up with your setup:
The roof surface of the gazebo shows up single-sided, just like on your screenshots, so that is probably not down to your graphics adapter.
I have varied experiences with two-sided surfaces myself - sometimes they work, sometimes I have to make an opposite normal duplicate. Haven't managed to spot a pattern...
Looks like there is a duplicate of a surface in one of the wallsections of the bridge (third from the end on the right, facing pagoda island), with the two copies fighting it out over Z domination. :7
There are some strange "half-polygons" covering the windows on the top floor of the pagoda.
Looks beautiful otherwise - I take it the solid diagonal bit on the balustrades is a design feature?
Yes, by the way; I suppose we might have guessed that the granite texture is a placeholder, seeing the prominent watermarking. :)
Personally I'd love to see this age as a Eder Delin-like setting rather than the tiny-islands-in-a-vast-sea formula -- either enclosed like Delin, or perched high on a mountainside like Eder Licinius.
(I'm afraid that I haven't even loaded Yaeviev into Blender since last we spoke about it, yonks ago, by the way - sorry, I'm such a lazy bastard. :/ )