There is a feature in windows machine where the Microsoft reserves your some percentage of your internet bandwidth speed. QoS packet scheduler Provides traffic control on a network using IPSEC and applications and equipment supporting the quality of service. The service also manages the quality of bandwidth. In fact the service is expected to provide a kind of intelligent allocation of bandwidth between applications where the need is greatest. for this purpose the 20% is also has been denied by Microsoft. If you do not use netmeeting or windows media player (to play internet stream, streaming) you can disable it.

For this,

  • go to run (Win +R )
  • in the run-box type in gpedit.msc
  • A Group Policy window appears. Go to Computer Configuration > Administrative Template > Network. Open QoS packet scheduler and select limit reservable bandwidth and put the value ( between 0-100 ) in the Bandwidth limit % box. Minimum value ensure greater increase in internet speed or you can disable it by selecting not configured.

QoS feature  is not available in Window 7.