We have a remote site connected to the main office via a site to site VPN. Main office has a very beefy terminal server with a separate Dell DAS device and a fast coax internet connection. The remote site has very few internet options. We're running a 40mb down, 10mb up connection for them now. The issue we're having is that the users at the remote site have dual 4k resolution monitors and when they are viewing large PDF's of building plans, the scrolling is very slow. Also, switching between programs on the TS is slow. We can't lower the screen quality because they need to be able to see the plans at max resolution. They also access 2 or 3 applications that access a database at the main location. So once the software opens on the TS, it's much faster than using it over the VPN.
Would a Sonicwall WAN accelerator help? What else could I look at doing to increase response times on the terminal server but not reduce image quality?