QoS (Quality Of Service) Bandwidth Reserve Setting

Windows XP reserves 20% of the connection bandwidth for QoS traffic. This tweak allows the setting to be altered to a different percentage of connection bandwidth. If the system uses more than a single adapter for network connections, each adapter may be set individually by navigating to:

HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesPschedParametersAdaptersAdpater-ID rather than HKEY_LOCAL_MACHINESOFTWAREPoliciesMicrosoftWindowsPsched

Start Run Regedit

Go to: HKEY_LOCAL_MACHINESOFTWAREPoliciesMicrosoftWindowsPsched

Modify/Create DWORD Value of Data type REG_DWORD Named NonBestEffortLimit
Setting for Value Data: Enter as a Percentage / Default Value = 20

Exit Registry / Reboot

source:here