Why shared folder with excel files from other computers are very slow to open on my computer? Computers have the same operating system and Microsoft version (excel 2007).
This may have multiple causes like large files, spending time on validation process, scanning for viruses. To fix this, you can try to check your antivirus trust list and try to add the Excel files on it. Also, you can go inside Excel software, to Options -> Advanced -> and check "Ignore other applications that use Dynamic Data Exchange (DDE)". This may solve your problem.
Also, for more informations about this matter you can visit the following official link :
http://social.technet.microsoft.com/Forums/office/en-US/1a1ffe77-f121-4563-8c94-6aca8b470ff0/slow-access-when-opening-xls-or-doc-files-over-the-network-but-xlsx-and-docx-files-are-fast?forum=officeitproprevious