Folder Redirection, VPN and Performance

HI,

I?m running the following topology and facing a couple of problems, I have 2 remote sites connected to our main offices via VPN, we are using site to site connectivity over Sonicwall boxes.
Our DC is a windows 2008 32 bit server standard.
I want to use Folder redirection, as users might swap their locations.
My main problem that it is it taking a long time for users login and accessing files while they are online.
Any design help is highly appreciated

Thanks and best regards