In Word select "save as" from the "file" menu, open the "tools" sub-menu and choose "compress pictures" choosing either "print" or "screen" depending the quality you need. Then continue to save the file with a new name.
This may well reduce the file size considerably and make the upload and conversion to PDF much quicker. Same trick works with PowerPoint and I believe Excel. I encourage people to do with all their DOC and PPT files at work, saves server space.
Hope that might help.