I recently upgraded my operating system from Windows XP to Windows 7. I did a clean install of Windows 7 and everything was running smoothly. When I started playing Team Fortress 2, however, I noticed that the game lags behind about a second or so even though my ping times were normal ( < 100 ms).

After a while of playing, I got really frustrated and decided to do something about the lag. I checked the netgraph and noticed the connection was choking. After researching possible causes of this, I came to a conclusion. Windows 7 packs a lot of unnecessary services and one of those services, Multimedia Class Scheduler service, was causing source engine-based games to lag. After disabling the Multimedia Class Scheduler service, I was finally able to play and enjoy Team Fortress 2 without the annoying lag.

How to disable Multimedia Class Scheduler service in Windows 7

1. Press the start button
2. Type in services.msc and press enter
3. Scroll down until you find Multimedia Class Scheduler
4. Right Click it and click properties
5. Where it says Startup type, choose Disabled

The Multimedia Class Scheduler service, however, is required for the windows audio service meaning you will not have sound without it, but you can change this by following these steps:

1. Click on the start button
2. Type in regedit and press enter
3. Navigate to HKEY_LOCAL_MACHINESYSTEMCurrentControlSetservicesAudiosrv
4. Right click on DependOnService and click modify
5. Remove the line MMCSS
6. Restart your computer