When you have a virtual machine that has the Large Send Offload (LSO) feature of Hyper-V Network Virtualization enabled, network communication is very slow.
This problem occurs because of an issue in the LSO feature of Hyper-V Network Virtualization. The Push bit is not being propagated correctly, and this causes the push timer to be invoked.
Hotfix informationA supported hotfix is available from Microsoft Support. However, this hotfix is intended to correct only the problem that is described in this article. Apply this hotfix only to systems that are experiencing the problem described in this article. This hotfix might receive additional testing. Therefore, if you are not severely affected by this problem, we recommend that you wait for the next software update that contains this hotfix.
If the hotfix is available for download, there is a "Hotfix download available" section at the top of this Knowledge Base article. If this section does not appear, contact Microsoft Customer Service and Support to obtain the hotfix.
Note If additional issues occur or if any troubleshooting is required, you might have to create a separate service request. The usual support costs will apply to additional support questions and issues that do not qualify for this specific hotfix. For a complete list of Microsoft Customer Service and Support telephone numbers or to create a separate service request, go to the following Microsoft website: Note The "Hotfix download available" form displays the languages for which the hotfix is available. If you do not see your language, it is because a hotfix is not available for that language.
PrerequisitesTo apply this hotfix, you must be running Windows 8.1 or Windows Server 2012 R2.
Additionally, you must first install update 2919355 on Windows 8.1 or Windows Server 2012 R2.
Restart requirementYou must restart the computer after you apply this hotfix.
Hotfix replacement informationThis hotfix does not replace any previously released hotfix.
Microsoft has confirmed that this is a problem in the Microsoft products that are listed in the "Applies to" section.