This is unusual. I checked my internet speed in Opera using Shaw Speedtest and found that I was getting low download speed, around 100 instead of 150. I called Shaw support and determined that I was getting good throughput and there wasn't a problem on their end. I checked my own equipment and couldn't find anything wrong. So I tried shaw speedtest in Firefox and got a down speed of over 170. I then tried speedtest.net, still in Firefox, and got similar results. So I went back to Opera, tried speeedtest.net, and got the same poor results I got with shaw speedtest.
I then tried Internet Explorer. With Shaw speedtest I got poor results similar to what I got in Opera. But when I tried speedtest.net I got excellent results, similar to Firefox. To sum up;
Opera Shaw D 105.9 Mbs U 16.2 Mbs
Speedtest.net D 103.1 U 16.16
Firefox Shaw D 178.1 U 15.0
Speedtest.net D 178.65 U 16.28
IE Shaw D 112.3 U 15.3
Speedtest.net D 178.72 U 16.29
Why these differences and how do you objectively get an accurate reading of actual internet speed ?