Solidworks defaults to 'Software OpenGL' when you access its PC via Remote Desktop - this probably explains the slow response. However, if someone starts SW on the remote PC, then you access that PC (using the same login) using Remote Desktop, the graphics card is used instead of it flipping to Software OpenGL.
The internet connection where your CAD computer resides must have a good upload speed. The upload is what is sending the screen images to your remote computer. Many ISPs have high download speeds, like 10, 20, or 50 Mbps download but only have 1.5kbps upload speed. If you go to speedtest.net on your CAD computer you can verify the upload and download speeds.
We use a VPN and remote desktop to connect to computers. There are other ways your IT guy may accomplish the task and there could be a weak link there too. I'm not an expert at the networking aspects but we have gigabit ethernet connections and relatively modern servers, routers and switches which may all play into the speed of the connection.
Yes and Solidworks will default to Open GL but I haven't had a problem with it myself. Our remote connections are very fast even with multiple users simultaneously connected. We have a 10Mbps up and 10Mbps down speed. Hope that helps.