Yeah the smart thing to do is schedule "important" user submitted images for heavier recompression, but even then you might get in trouble for very large PNGs,

Yeah the smart thing to do is schedule "important" user submitted images for heavier recompression, but even then you might get in trouble for very large PNGs, and need to gate based on dimensions. For huge PNGs I am not sure the 80x - 160x time penalty is tenable, you might be talking 30 minutes in some cases.