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Is VLC taking an agonizingly long time to start up on Windows 11? Microsoft Defender is to blame

Philipp Briel
Philipp Briel · 5 min. read

In some cases, users opening an MP3 file with VLC on Windows 11 may have to wait up to 33 seconds for playback to start. According to VideoLAN, this is not due to a flaw in the player itself, but rather a bug in Microsoft Defender that blocks VLC’s plugin cache. The developers are thus refuting the claim that open-source software is fundamentally unreliable.

In short:

  • On affected Windows 11 systems, VLC takes up to 33 seconds to play an MP3 file.
  • VideoLAN blames a bug in Microsoft Defender that quarantines VLC’s plugin cache.
  • The public debate was sparked by a critical post from game developer Jonathan Blow.
  • Workaround: Add the VLC folder as an exception in Windows Defender or regenerate the plugin cache.

The trigger: A tweet from Jonathan Blow

The story began with a public complaint. Game developer Jonathan Blow, known for titles such as Braid and The Witness, posted on X that VLC took him 33 seconds to play a single MP3 file. His response: He promptly switched to Windows Media Player and used the incident to question the state of open-source software on Windows in general.

He experienced the problem on a Ryzen 9 9800X3D with 32 GB of DDR5 RAM—hardly underpowered hardware. Other users reported similar delays, sometimes around 24 seconds, even on Windows 10. For comparison, Blow cited the built-in Windows Media Player, which uses about 377 MB of RAM when idle but launches without any delay.

The Cause: How Microsoft Defender on Windows 11 Cripples VLC’s Plugin Cache

VideoLAN responded promptly and publicly on X. The key takeaway: A Windows 11 update introduced a bug in Microsoft Defender that incorrectly quarantines VLC’s plugin cache file. VLC does not load codecs, demuxers, and input/output modules as a single compiled binary file, but rather from a cache called plugins.dat as needed. If this file is blocked by Defender or its release is delayed, it takes a correspondingly long time for VLC to even figure out which module it needs for an MP3 file.

The exact technical mechanism behind this has not yet been fully clarified, but reports indicate the problem has existed for over a year. Faulty Defender updates that mistakenly block legitimate software are not an isolated incident, as similar Windows Update issues have repeatedly shown.

VideoLAN Responds: “Open Source Isn’t the Problem”

VideoLAN was particularly clear in its response to Blow’s criticism of open-source software. In a post on X, they essentially stated that the issue was caused by a “bug” in Microsoft Defender within a Windows 11 update, which had somehow quarantined VLC’s plugin cache. Reinstalling VLC or regenerating the plugin cache would resolve the problem. The developers also openly criticized the notion of calling open-source software “embarrassing” when the actual cause was a Windows bug.

There has been no official statement from Microsoft regarding the incident so far. It is noteworthy, however, that a community comment under Blow’s original post confirmed that adding a Defender exception for the VLC folder does indeed resolve the issue, which supports VideoLAN’s account of the situation.

Here’s how to fix the problem yourself

If you’re affected, you have three options, with the first one having the fewest side effects:

  1. Set up a Defender exclusion: Open Windows Security, navigate to “Virus & Threat Protection” and “Manage settings,” and add the VLC installation folder (usually C:\Program Files\VideoLAN) as an exclusion.
  2. Rebuild the plugin cache: Search for “VLC media player – reset preferences and cache files” in the Start menu, or run the vlc-cache-gen.exe file in the installation folder. Note: This will cause you to lose custom settings such as the equalizer, keyboard shortcuts, and subtitle configuration.
  3. Reinstall VLC: Download the latest version from the official VideoLAN website and perform a clean reinstallation of VLC if the first two steps do not resolve the issue.

Users who tested the Defender exception report that it reduced the loading time from several seconds to less than one second, which supports the theory of a Defender bug.

Conclusion

This case demonstrates one thing above all: Before hastily blaming open-source software for poor performance, it’s worth taking a look at your own system configuration. A Windows Defender bug that has existed for over a year and apparently only came to light through a viral post also raises the question of how thoroughly Microsoft tests its own security updates against established third-party software. Until an official statement is issued, the only solution is the manual workaround.

Sources:Windows Central, VideoLAN on X