When you export via EG table viewer export, EG and your PC are reading the table from the server and then writing out the Excel workbook to the folder of your choice. You are limited to the processing ability of your PC and the speed it can read and write data across your network. There is not really much you can do to speed it up.
Your SAS server can do this much faster so that is the best option. Even if you don't have SAS/ACCESS to PC Files you can still export CSV's which Excel can read.