Tronspir, certainly the graphics engine can be improved in performance also, while adding more effects, textures, etc. I dont know where the problem is, perhaps in the number of polygons used per object, but the fact is that older sims with better graphics are less CPU/VCard dependant than AH. If the main problem is in the number of polygons used per object/plane, etc, IMO, halfving that number will give us almost the same visual effects but much more free CPU. Most of the time we are flying without external views and we normally see the enemies at no less than 200 yards (except when crashing), so, a zillion of polys does not really matter. What do we want, a plane modeling each screw or 20 fps more?
What we badly need is a system where we can choose the complexity of the 3D models. Do u have a K7 2Ghz? Ok, select the zyllionpoly mode. Do u have a PIII 500? Select a more simpler mode. That way more people will be happy with their current systems, but HTC team will need to model each plane twice (at least for close ranges).
For example, the detail that u can see from inside a Lancaster cockpit (forward view) is no much more than the detail seen from a P51 cockpit, but, for some reason, the difference in FPS is really noticeable. Too much invisible polygons or polygons that are there for nothing are being taken into account in the rendering process.