Antivirus Exclusions and the Teams Desktop Client

Balancing Security and Performance for the Teams Client

When it comes to antivirus software, it’s important to maintain a balance between system security and the usability and performance of applications. AV software can inspect literally everything that happens on a workstation in an attempt to detect and disinfect any potential threat as soon as it appears. Antivirus activity can consumes many CPU cycles and cause delays when applications access heavily-used (“hot”) files, which is why Microsoft recommends excluding some system files from scanning. ISVs make the same sort of recommendation for important files used by their products (here’s an example from CommVault).

Which brings me to the Teams client and the files that it depends on, notably locally cached data. The Teams client is not known for its swift performance and low memory use. In fact, just like Outlook desktop was accused of being a “fat pig” in its heyday, the Teams client is often referred to in similar pejorative terms. To be fair to the Teams developers, although the desktop client seemed to have an unlimited appetite for memory in the past, that demand has been trimmed recently. It’s still not a slim client, but it’s definitely not as fat as it used to be.

Excluding Important Teams Files from Windows Defender

In any case, when complaining that the Teams desktop client occasionally “stuttered” especially when the client retrieved older chats for display, it was suggested to me that I should consider excluding some important Teams files and folders from antivirus scanning. I use Windows Defender on all my PCs, so the exclusions are handled through system settings (Figure 1). Other antivirus products handle exclusions in a different manner.

Excluding Teams files and folders from Windows Defender
Figure 1: Excluding Teams files and folders from Windows Defender

The suggested files and folders to exclude are:

  • Teams.exe (the Teams executable).
  • Update.exe (the executable that updates the Teams client).
  • %Appdata%\Microsoft\Teams (the Teams root data folder, which includes the Cache folder)
  • %LocalAppData%\Microsoft\Teams (where Teams stores files for updates in the Packages folder)

I’ve been running with these exclusions for a couple of weeks and although I cannot say that I have noticed any great increase in performance, I can likewise say that I haven’t seen any problems either. It still takes a little time for the client to retrieve and display old chats, but my unscientific perception is that the display is smoother.

The decision about how to balance security and performance is yours. In my case, I’m happy to run with these exclusions in place. Your views are invited!


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6 Replies to “Antivirus Exclusions and the Teams Desktop Client”

  1. Excluding exe files beats the reason of having resident antivirus. In theory teams.exe can be infected with some malware and AV won’t do anything.

    1. That’s certainly a possibility that needs to be considered as you make these decisions. As with many issues to do with security, you sometimes need to trade total security against performance.

  2. @Tony The suggested files and folders to exclude, is this suggested by Microsoft or what is the conclusion for making this statement?
    Still I’m surprised there is no official guide from Microsoft for this topic so thanks for bringing it up.

    1. The suggestion came from a member of the Teams development group in response to some questions about speeding client performance. Microsoft doesn’t tend to issue application-specific guidelines for anti-virus exclusions.

  3. There should be no need to exclude update.exe since it’s covered by %LocalAppData%\Microsoft\Teams.

    There might be an argument to use the exclude “process” feature on it (and teams.exe, for that matter). I assume that’s for when AV is hurting a given process on an ongoing basis as opposed to just when it’s being read from disk.

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