The first thing I would look at is the size of the profile. By default, outlook will store the archive folder into the profile folder. If this gets rather large it can really slow down the logon process (as I found out). I eventually gave up on profiles and just turned mine off. I found too many weird problems that popped up because of them. You can test if this is the problem simply by turning off the profile for that user and logon again and compare the times.