Disabling/Tweaking Vista’s Multimedia Class Scheduler

One of the most frequent complains about Windows Vista is the Multimedia Class Scheduler (MCS). The is an enabled-by-default component in Windows that prioritises multimedia applications and tasks such as video and music playback (hence, improving your multimedia experience).

However, when multimedia tasks are active (most notably if Windows Media Player is active), MCS will throttle down the global network bandwidth to around 10,000 packets per second to conserve CPU interrupts. On high speed links like Gigabit Ethernet (without Jumbo Packets), the throttling may yield a significant drop in network throughput.

In Vista SP1, Microsoft added the ability to change the packet per second limit of the MCS, or completely disable it. If you’re still using Vista RTM, you’re out of luck. The following procedures work with all new Microsoft operating systems, be it Vista SPx or Windows 7. 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 and above.

9 thoughts on “Disabling/Tweaking Vista’s Multimedia Class Scheduler”

  1. Make sure you’re using Windows Vista SP1 and above
    HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Multimedia\SystemProfile

  2. Cool… i had 150 letency in cs, now when i change to FFFFFFFF i have 40-50 latency, btw i use win7 ultimate and it worked…

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