Thanks for getting back to us - I should have said we're rasterizing the pages, not extracting images. This is the version information from PDF Demo (also very slow!)
Atalasoft.dotImage.WinControls - 4.0.2517.25813
Atalasoft.dotImage.PdfRasterizer - 4.0.2517.25813
Atalasoft.dotImage - 4.0.2517.25813
Atalasoft.dotImage.Pdf - 4.0.2517.25813