I often hear that when playing network game in Win7, network time delay often happens, namely, it takes more time to ping than normal time. And I’ve been searching reasons for that, but still have no clue. It’s really annoying. Today, finally I found the reason, it is a service of Win 7: Multimedia Class Scheduler.
 And here’s the official explanation:
　　The Multimedia Class Scheduler service (MMCSS) enables multimedia applications to ensure that their time-sensitive processing receives prioritized access to CPU resources. This service enables multimedia applications to utilize as much of the CPU as possible without denying CPU resources to lower-priority applications.
　　MMCSS uses information stored in the registry to identify supported tasks and determine the relative priority of threads performing these tasks. Each thread that is performing work related to a particular task calls the AvSetMmMaxThreadCharacteristics or AvSetMmThreadCharacteristics function to inform MMCSS that it is working on that task.
　　For an example of a program that uses MMCSS, see Exclusive-Mode Streams
It is the service taking me much time to ping. Here is the problem, so how to solve it? Quite easy, just disable it.
   And here’s the method to disable: start—run, type “Regedit”, expand [HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Services/Audiosrv], double click the DependOnService item on the right side, delete MMC