Now QuarkXPress 10 displays the images in Adaptive Resolution which is the best resolution to display the images. Adaptive Resolution in QuarkXPress 10 means the graphics are rendered in real time in the highest required resolution to match image zoom, crop and position. Designers no longer have to concern themselves with preview resolution settings and screen performance.
This is As Design feature of QuarkXPress 10, so relatively the document created from the legacy version of QuarkXPress 7 to 9 when opened in QuarkXPress 10 will re-import the images into Full-Resolution which will result in increasing the overall file size. There is no option available to display the images in low-resolution in QuarkXPress 10.
There is no fixed formula how much file size will increase as it is directly dependent on the image format and resolution. Higher the image resolution & file size will result in high document size. E.g. A QuarkXPress 7,8 or 9 file with the file size of 70 MB, when opened and re-saved in QuarkXPress 10 can go up 140 MB which is almost double the file size, however there might be files which can go beyond this too based on the image resolution and size.