Disabling/Tweaking Vista’s Multimedia Class Scheduler

One of the most frequent complains about Windows Vista is the Multimedia Class Scheduler. The is an enabled-by-default component that prioritises multimedia applications and tasks such as video and music playback.

However, when multimedia tasks are active, MCS will throttle down the global network bandwidth to around 10,000 packets per second. On high speed links like 100Mbps full duplex and 1000Mbps LAN connections that doesn’t use Jumbo Packets, the throttling may be significant drop network throughput.

In Vista SP1, Microsoft added the ability to change the packet per second limit of the MCS, or completely disable it. Here’s how:

1. Press Windows key and R simultaneously.

2. Enter “regedit” (without the quotation marks) and press enter.

3. Using the tree on your left, navigate to the following branch:

Computer\HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\ Multimedia\SystemProfile

4. Double click on “NetworkThrottlingIndex“.

5. To disable completely, enter FFFFFF with base hexadecimal.

6. To let say, 100,000 packets through per second, enter 100000 with base decimal.

7. Click Ok and restart your computer.

Note: This works only on Windows Vista operating systems with SP1 installed.