Since I moved to an Exchange account a few weeks ago I have noticed that it can take up to 25 seconds to open a PDF attachment in Adobe Reader X. I have looked into the situation and the characteristics are:

Time to open an attachment: 25 sec for PDFs but ~1-2 sec for all other file types
For my POP accounts on the same laptop all files open in 1-2 sec

If I open a PDF attachment, close it and then open it again within 1 minute then it opens almost instantly. If I wait about 5 minutes before opening it again it again takes about 25 sec; this doesn't seem to depend on whether I have opened other PDF files during that time.

The reason that this is a problem for me is that we have a central document scanner that e-mails the scans as PDFs to me and spending so long waiting for documents to open gets stale very quickly when you have 10 or more files you need to process. Any ideas or is this some inherent issue with PDFs on an Exchange account? I should say that we are a small company and the Exchange account is provided by a third party so I don't have a friendly Admin person to talk to about this.