Generated PDF sizes between 6.3.2 and 6.7.1

[NeilC]

We've recently updated from 6.3.2 (target framework 2-3.5) to 6.7.1 (target framework 4) and are noticing that the conversion code (comparing the same code but PDFNET 6.3.2 v 6.7.1) is consistently producing larger PDF sizes by circa 15-30k. We already run the generated pdf through the SDK optimizer as follows:

private static void OptimizeDocument(PDFDoc pdfDoc)

        {

            var txt = new Optimizer.TextSettings();

            txt.SubsetFonts(true);

            var settings = new Optimizer.OptimizerSettings();

            settings.SetTextSettings(txt);

            Optimizer.Optimize(pdfDoc, settings);

        }

Is this expected (the increased size) or should has something happened to the optimizer between releases. I've attached examples of the output from pdfnet 6.3.2 and 6.7.1 as an example.  Is there anything else that should be done to reduce the output size of the PDF.  Although individually the size is not great, the users produce 100's of documents a day and these are stored in a database, so keeping the PDF small is paramount.