Bitwarden Firefox Extension (v2025.10.0–v2025.11.2) High CPU Usage on Enable/Idle

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Enabling the Bitwarden Firefox extension causes an initial CPU spike (up to 50%) followed by consistently elevated background CPU usage (12-20%) while the browser is otherwise idle. Disabling the extension immediately resolves the issue, dropping CPU usage back below 10%.

  • Browser: Firefox 145.0.2
  • Bitwarden Extension: 2025.11.1
  • Issue Started with Version 2025.10.0
  • Windows 10: 22H2 (OS Build 19045.6575)

Steps to Reproduce

  1. Open Firefox with the Bitwarden extension currently disabled.

  2. Open your operating system’s Task Manager (or equivalent CPU monitoring tool) and monitor Firefox’s CPU usage. (CPU usage should be stable, below 10%).

  3. Go to the Firefox Extensions page.

  4. Enable the Bitwarden extension.

  5. Observe the CPU usage in the Task Manager immediately after enabling the extension.

Expected Result:

After a brief initial load, the Bitwarden extension should have minimal, transient CPU usage, allowing the overall Firefox process to return to a low idle state (below 10%).

Actual Result:

  1. Upon enabling the extension, the Firefox CPU usage spikes up to approximately 50% for a brief period (a few seconds).

  2. The CPU usage then drops to and remains consistently elevated in the 12−20% range, even when the browser is otherwise idle and the extension vault is locked.

  3. This elevated usage persists until the extension is manually disabled. The user perceives a noticeable slowdown and performance impact.

Note: Uninstalling and reinstalling the extension doesn’t resolve the issue.

2

Hi John,

Since Bitwarden follows up on bug reports more on GitHub, I would recommend that you post the details there instead of here. Typically, unless it’s widespread (or likely if it happens to the developers), this kind of issue may sit around for a while. I would personally roll back to whatever previous version that works and park there for a bit.

Issues on Github that may be related:

3

I actually don’t have a GitHub account, that’s why I reported it here.

But I think it’s time that I also make one at this point^^

I would personally roll back to whatever previous version that works and park there for a bit.

How do I do that?

And would this come with any security disadvantages if I roll back to an older version?

4

Go to the Bitwarden extension info page in Firefox Adds-on store, and search for “See all versions” or use this link: https://addons.mozilla.org/en-US/firefox/addon/bitwarden-password-manager/versions/

Do turn-off the automatic update on Bitwarden extension at: about:addons (paste in address bar).

Yes, you won’t get any “security” updates while on a non-updated version. On the other hand, if you pay attention to either GitHub release notices or new release notifications here in the forum, you can always try to upgrade (and then downgrade if necessary). This is obviously not ideal, but it’s a workaround until it works or you find something else that does.

5

You may also experience compatibility issues, as per Bitwarden’s software support policy:

“Each server version is compatible with clients of the same major version, the previous 2 major client versions, and the subsequent 2 major client versions.”

For example, the cloud server is currently on version 2025.11.1, which is only guaranteed to be compatible with browser extension versions 2025.9.0–2026.1.x.

That being said, I do have an old version (2024.11.2) of the browser extension installed in Firefox, and it seems to be working OK.

6

Thanks for this info! I didn’t know that.

I just rolled back to 2025.9.0, let’s see.

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