Windows Defender Real Time Protection Service slowing down Visual Studio etc

I had the same symptoms and my problem was fixed by disabling logs in Microsoft .Net Framework Assembly Binding Log Viewer (FUSLOGVW.exe). I forgot that I was running a test and left logging on.

  1. Run the viewer as administrator.
  2. Click Settings button.
  3. Check Log Disabled

Try excluding Visual Studio related file types from Windows Defender like this person did for Delphi:

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If you are cool with no protection at all you could disable Windows Defender, but I wouldn't recommend it.