Hi, a suggestion 1st : there is about 90% of the add-ons have something that works the same, is the same or several check your add-ons in this first to see how many or a alternative : https://addons.mozilla.org/en-US/firefox/extensions/ There is usserChrome which you can use to change how fire fox looks and does in about 235 million ways. A info page/sample links in it. https://www.howtogeek.com/334716/how-to-customize-firefoxs-user-interface-with-userchrome.css/ Firefox 58+ has protection from the meltdown issue : https://www.theinquirer.net/inquirer/news/3023893/opera-mozilla-vivaldi-and-more-rush-to-patch-spectre-and-meltdown-security-holes Also a new PC warrants having a multi-processor and multi-thread browser running on it which is only Firefox. But if you want to run 56 that is a security risk and gets no updates and will be forced to update to ver 57+ you can find it here, just pick your language : https://ftp.mozilla.org/pub/firefox/releases/56.0.2/win64/ Please let us know if this solved your issue or if need further assistance.