Hey there i run an exchange server 2010 and my clients use windows 7/4Gbram/ outlook 2010 with their ost's stored locally. Outlook starts up very slowly for most of then. Now many of them have extreme large mailboxes (20gb and more), i figure that would be the problem for the slow starting up.. or is there more i should look at?

Hi Large sizes are a cause of poor performance in Outlook but the item count can also cause problems. If you have more than 5000 items in the target folders (Inbox, Calendar, Sent Items etc.) then you may see slow startup and browsing/changing between folders. Sometimes breaking down folders with more than 5000 items into separate sub-folders will help. Cheers, Steve

Have you tried in safe mode and tested? Also, check to see if they are in cache mode or online mode, test in both modes. See if some of them are opening many shared mailboxes and if they are being downloaded too, if they are untick those and check again. Also, check MAPI objFolder counts, to make sure they aren't exceeding this if they have shared mailboxes.Sukh

Hi Large sizes are a cause of poor performance in Outlook but the item count can also cause problems. If you have more than 5000 items in the target folders (Inbox, Calendar, Sent Items etc.) then you may see slow startup and browsing/changing between folders. Sometimes breaking down folders with more than 5000 items into separate sub-folders will help. Cheers, Steve

Have you tried in safe mode and tested? Also, check to see if they are in cache mode or online mode, test in both modes. See if some of them are opening many shared mailboxes and if they are being downloaded too, if they are untick those and check again. Also, check MAPI objFolder counts, to make sure they aren't exceeding this if they have shared mailboxes.Sukh