How to disable FireFox’s built in antivirus scanning

In Windows Firefox automatically uses the local virus scanner, if installed, to scan any file it downloads. While this may provide extra safety, the real-time scanning functions of modern antivirus programs render this additional scanning unnecessary and causes delays, false positives and even freezes when downloading files – especially large ones.

To disable Firefox's automatic virus scanning perform the following steps:

  1. In the address bar type about:config
  2. In the filter bar (CTRL+F) type browser.download.manager.scanWhenDone
  3. Double click this entry to toggle it from the default true to false
  4. Close all open Firefox windows and restart to apply the change
How to disable FireFox’s built in antivirus scanning