It's possible that the anti-virus is checking the file when it's first opened. Also, the file is not very volatile, and so more and more of it will be cached in memory as inquiries are done. Also, it given the wide variation in the times, perhaps Windows is running out of memory and starts paging applications to disk. Look specifically for Outlook, and ask the order that the applications are loaded. Outlook grabs all the memory it can when it starts, there may be little left over for Adagio.

Perhaps it's time to purge some of that history?