Normal speed is 2.3 Mbps but i reached 6.7 mbps while downloading R6S?

[ETIMESGUT]

My usual download speed is 2.3 Mbps but a couple weeks ago when i downloaded R6S i left my pc open for the night and when i looked at the average download speed the other morning it said 6.7 mbps. Does anyone know how it reached this speed?