In the PDF Optimizer, there are separate settings for Images and document structure. Image quality you want to preserve (high DPI, etc.), while the document structure you want to simplify as much as possible. (e.g., under Discard Objects check everything. Also try flattening transparency and shifting the slider toward Raster).
Sorry about plugging my own little script, but I do think it's very useful for this specific issue of long page turns. Check out
this thread.