I'd like to see your layer images. I hear complaints about slowdown sometimes, but it's almost inevitably due to poor optimization. I have over 20 moving layers in some projects I'm working on, with several of them using affine transform, and there's not even a hint of slowdown.
Often times you will get better performance from more layers, not less, if it means you can break them into smaller pieces with less areas of transpareny the engine can't trim. I'm talking about the fully transparent areas, not alpha blending.
DC