Diễn đàn hỗ trợ Firefox

I’m working on improving the performance and search visibility of a WordPress website and would like to understand how Firefox handles modern websites from a performance and user-experience perspective.

Are there specific Firefox tools, developer features, or recommended practices that can help identify issues such as slow page loading, large images, JavaScript-related delays, layout problems, or other factors that may affect the browsing experience?

I’m particularly interested in practical steps that a website owner or developer can use when testing a responsive WordPress website across desktop and mobile browsers.

I’d appreciate any recommendations for Firefox Developer Tools or documentation that can help with this type of website testing.

The first time after setup I selected UK as location so that I could visit BBC.co.uk rather than the Americanised version of the site (.com). The second time I signed on, the UK option and most others had disappeared. Now no option works for me. Each option redirects me to BBC.COM. How can I get back the other options?

Server Not Found

Firefox can’t connect to the server at legalfolder.sce.com. What can you do about it?

   Check to make sure you’ve typed the website address correctly and try again in a few moments.
   Check your network connection.
   Check that Firefox has permission to access the web (you might be connected but behind a firewall).

https://www.optimist.com/ip

Peer’s Certificate issuer is not recognized.

HTTP Strict Transport Security: false HTTP Public Key Pinning: false

Certificate chain:

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In the past couple of weeks (say Sept 2026), Firefox has started signing me out of everything when it closes or updates even though 'clear browsing data' is UNchecked. What else can I do to stop this?

I have setup my Firefox browser to start on a number of pages, using the settings provided in the browser. Recently Google / Youtube started complaining, that my browsing is suspicious

"This page appears when Google automatically detects requests coming from your computer network which appear to be in violation of the Terms of Service. The block will expire shortly after those requests stop."

Which came instead of this url URL: https://www.youtube.com/watch?v=e-zj5cedG-A

I worked around it, by copying the url and pasting it in the browser again But today, it returns the error no matter how many times I manually paste the url in the browser.

I have effectively been blocked from all my startup Youtube pages

The subject line of replies to email messages are preceded with Aw: instead of Re:. Aw: appears to be the German language version of Re:, but my language is set to English as best as I can determine. Forwarded email are preceded with Fw: as normal. My other email (Yahoo mail) does not have this problem. I do not see anything other than the Subject line Aw: that looks like it is in another language. If I use a different browser (I usually use Firefox,) the same problem occurs so I do not think it is a browser setting. It only happens in my mail.com account so I do not think it is a global Windows setting. This problem started several months ago -- I have been using mail.com for many years without this problem so it appears to be caused by a mail.com update. Thanks.