look close and be sure you know what numbers you are looking at. speedtest reports as megabit per second usually. while when you download, it is usually reported in megaBYTES per second. there is a difference. 8 bits = 1 byte. so 68 mbits = a bit over 8 mbytes per second.
so 6.5 mbytes/second is pretty good for that mbits per second reported. assuming i am right in guessing what you are seeing.