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Poor Performance and Freezing in Firefox


I have been using Languagetool Pro for quite some time now and it has been working fine. Lately however, I have installed Firefox along of Brave, which is my main browser. The reason is, that for web development I need it.

Languagetool however on Firefox seems to be really laggy when used with Google Docs. There are long lags and freezes followed by a yellow notification, that a script error has occurred. The options are to wait or to stop the script or to disable the extension in the settings.

Even in general, if I type without the tool in Google Docs, it is super fast. If the tool is one, it’s all laggy and it takes one to two seconds for the words or letters to appear. No fun, to be honest. Any idea, what is causing this? Any fixes planned maybe?

Hi Ben, thanks for your feedback. We’re not aware of major performance issues in Google Docs. Is your document particularly long? Is there a chance you could share it with us privately?

Hi, thanks for the reply.

My documents are usually around 1500 to 5000 words long. So nothing special.

On Brave, I did some spell checking work on documents with 50k words and it worked super fast and without issues. This seems to be particularly related to Firefox. I am also using the Firefox Developer Version on Linux, since I am a Web Developer.

I can also confirm, that there are no issues on Vivaldi, the third browser I am using.

Sure, I would be happy to share the document. Please let me know where to send the private link to.


Thanks, I’ve sent you a private message about sharing the document. Do you use any other add-ons in Firefox maybe? It’s rare, but sometimes add-ons can interfere with each other.

Hi, I sent you the link for sharing.

Please remove yourself after testing, as this is a client document.

I am using some extensions, but not much. Some of them I don’t need with Brave. The extensions in Firefox are:

  • 1Password (I use this one in Brave as well)
  • WordCount Tool (I also use that with Brave as well)
  • Google Translate (I use that in Firefox and in Brave)
  • Languagetool (obviously… on Firefox and Brave)
  • HTTPS Everywhere (Firefox only)
  • Adblock Plus (Firefox only)

Other than that, there is no extension and this is a fairly clean installation of FF, which is about five days old or so.


I can reproduce that editing is slightly laggy, but not to the point that the Firefox warning appears… I’ll discuss this with our developer in the next few days.

Thanks for getting back to me.

You could try the following: Copy the document to your drive so you have a copy, since this is a client document. Delete the content of one of the paragraphs. You can leave the headline, just delete the content. Then go and write a new paragraph. I am an avid typer, so I write kinda fast… usually after a sentence or two, it would hang and the warning would come up.

Other than that, thanks for your quick help!

I’ve deleted the paragraph “In Zeiten von finanzieller Unsicherheit…” and started typing, but still didn’t see the problem. Maybe a short screencast of the issue might help, but it’s probably something with your browser. Maybe you could use this link to submit feedback (referring to this thread), this way we’ll get more information (browser version etc.):


Hi, sorry for the delay. I have had a lot of work.

I have done what you asked for and sent an issue. I guess it doesn’t matter from which site I send it, right? I just linked to this thread.


Thanks, we have received the feedback. I’ll discuss with our developers to see if they have more ideas what the issue might be.

Thanks for the feedback. Please do.

I had the issue again with three other documents. But only, if those documents are long and with tables and images. They have all about 1500 to 2000 words and about six images plus two or three tables.

The issue does not appear on shorter texts I do, for example for spellchecking. Also, the issue does not appear outside of Google Docs and outside of Firefox. I can work on other sites, post on forums, etc. without any issue. I can also open the same Google Docs in Brave Browser and have no performance loss at all.

In case you are not aware: Brave is based on Chromium and hence related to Google. While Firefox is not. This could be reason for the issue. The other thing is that Brave by default blocks many trackers and scripts that Firefox does not block. That could help with the fast performance. Maybe this helps you.