Why my TP-Link TL-WN725N . only giving 3.5 Mbps speed ?

[RageshAntony]

I am having TP-Link TL-WN725N . It's only giving 3.5 Mbps in 50 Mbps connectiion

Whereas my Mobile Tethering , connected with the same hotspot giving 34 Mbps - 48 Mpbs to my PC.

Why ?