What are the major limitations?

[rivenwanderer]

Is there a section of the wiki or something that explains the features that have a large impact on the framerate? Number of polygons, number/size of textures, number of reflecting surfaces, number&types of lights, etc? If I'm brainstorming for an Age, I don't want to come up with something unmanageable right off the bat... I'm used to the mentality of "it doesn't matter how slow this is, once I render the final image", and I know that won't work if I'm designing for a game engine

[Shoggoth]

In general, all those things should be as low as possible, although I know Cyan uses a lot more polygons than people seem to think. If your Age is fairly small, you have fewer constraints on polycount. Most textures in Cyan's Ages (and most of the ones I've seen from other people, too) are around 512x512. Lights/shadows tend to cause the greatest reduction in framerate as far as I know, which is why you want to make sure that your materials are set not to cast real-time shadows. Only the avatar casts these, usually, and even this can cause slowing in some older computers. Shadows are better done with vertex shading and lightmaps. I'm not sure about specularity. I know that using a whole lot of specular surfaces will cause slowdown, but I don't know the upper limit. Again, if you can get away with less, do less.