well to check that safari is not going through the vpn you can do a little test.
make sure your not connected to the vpn and goto
http://whatismyip.com
take a note of your IP address.
Then connect to your vpn. Then refresh the page
http://whatismyip.com
If your ip address does not change then your safari traffic is not going through the vpn and then there maybe some other things we can do to find out where the bandwidth issue is.