I am highly suspicious of that speedtest.net report. I know the various speedtest.net servers around the world vary in performance, but I have never seen one show anything above about 600Mbps, and be highly variable. Our own 1Gbps internet service gives rates between about 200Mbps and 600Mbps on the speedtest.net servers connected to our local backbone, but I get a full 1Gbps to and from a number of other places at the same time of day.
That Cox service seems rather expensive at $79 a month, and it didn't seem clear who pays for the installation. We pay about $27 a month, and didn't have to pay for installation with a 24 month contract..