My assumption is that your login scripting is not working with wireless. Is everything the same functionally whether you are wired or wireless?
Also, if you login and logout multiple times while wired, does the 30 minute lag disappear? If so, perhaps it is a similar issue where your profile is being recreated on the server. That's really the only reason I would expect it to take that long would be transferring all the contents of your profile (My Documents, Desktop, Application Data, etc). Provided you are using roaming profiles, I would try logging onto a PC you have never used before and see how long it takes. I would imagine it would be a similar amount of time.
It should speed up to less than a minute or two after logging on twice. The first time you log-on, the profile on your PC is being created, and the Server is copy is being written to it. Then the next time you log-on, the local PC version is being copied to the server. After that just changes that are made are copied over on log on-and-off.
