Lightmapping anyone? No need to simulate per-pixel lighting. Sounds like you were fighting against the engine instead of working with it.I guess it could be for two reasons. First I had tried to emulate per-pixel lighting by using a relatively high number of triangles (at the time I was able to use up to 100K triangles in the entire scene and still get around 60fps).
And this is one of those 'general' questions about game programming. As such I'm placing it on the GD board.
When you have a specific 'real' question about code for game programming come back here and ask it.