I've done some reading and apparently the main obstacle to fast remote profile syncing is that Samba takes a long time to transfer lots of little files like cookies. After reading Roaming Profiles: Best Practices , I plan to use Folder Redirection, but I want my users to be able to login as rapidly as possible, even if it means that their data is still coming in when they reach their desktop. Is there a way to do this with GPO or a third party add-on that can load user profile data faster/speed up the login process for users?
...even if it means that their data is still coming in when they reach their desktop
This is referred to as profile streaming. It is implemented in third-party profile management products only, namely Citrix Profile Management, RTO Virtual Profiles (bought by VMware and currently not available) and Appsense Environment Manager. The only one of these products that is available independent of other products comes from Appsense, but be warned, it is not inexpensive.
If buying into a third-party product is not a possibility for you, I recommend you carefully analyze and optimize your roaming profiles. Here are some articles from my blog that may be helpful: