https://support.mozilla.org/en-US/kb/warning-unresponsive-script Warning Unresponsive script - What it means and how to fix it This article describes the reasons for this error message and covers possible solutions and workarounds.

Another common cause of unresponsive script errors on Windows 7-10 is the protected mode feature of the Flash player plugin. That feature has security benefits, but seems to have serious compatibility issues on some systems. You can disable it using the Add-ons page. Either:

• Ctrl+Shift+a
• "3-bar" menu button (or Tools menu) > Add-ons

In the left column, click Plugins. On the right side, find "Shockwave Flash" and click the More link. Then uncheck the box for "Enable Adobe Flash protected mode" and try that for a day to see whether it helps.

Note that Firefox uses the "chrome://" protocol to access its own internal files and also access files from extensions (no relation with Google Chrome).

• https://developer.mozilla.org/en/Chrome

In your case:

• view-source:chrome://browser/content/browser.js

Start Firefox in Safe Mode to check if one of the extensions ("3-bar" menu button/Tools > Add-ons > Extensions) or if hardware acceleration is causing the problem.

• Switch to the DEFAULT theme: "3-bar" menu button/Tools > Add-ons > Appearance
• Do NOT click the "Refresh Firefox" button on the Safe Mode start window

• https://support.mozilla.org/kb/Safe+Mode
• https://support.mozilla.org/kb/Troubleshooting+extensions+and+themes

There are scripts within Firefox. But also scripts from add-ons, other programs on your system (plugins), or even from the website you are accessing.

Thanks you, my browser running fast again