https://connect.mozilla.org/t5/discussions/firefox-158-is-slow/m-p/143462#M58710 <P><a href="https://connect.mozilla.org/t5/user/viewprofilepage/user-id/141978">@zeumendes1</a>&nbsp;: probably an extension</P><P>Test the sites you're finding slower in Menu -&gt; Help and Report -&gt; Troubleshoot Mode</P><P>If they run at normal-speed there, an extension is causing your issue normally.<BR />If you use any ad-blocker, script-blocker or page-themer (e.g. Dark Reader) extensions, try setting them to "off" on the pages with an issue and see which is causing the problem</P> Thu, 15 Oct 2026 09:52:50 GMT dftf 2026-10-15T09:52:50Z https://connect.mozilla.org/t5/discussions/firefox-158-is-slow/m-p/143252#M58642 <P>I got the 158 update today, and it is clearly slower than before</P> Wed, 14 Oct 2026 11:34:57 GMT https://connect.mozilla.org/t5/discussions/firefox-158-is-slow/m-p/143252#M58642 zeumendes1 2026-10-14T11:34:57Z https://connect.mozilla.org/t5/discussions/firefox-158-is-slow/m-p/143462#M58710 <P><a href="https://connect.mozilla.org/t5/user/viewprofilepage/user-id/141978">@zeumendes1</a>&nbsp;: probably an extension</P><P>Test the sites you're finding slower in Menu -&gt; Help and Report -&gt; Troubleshoot Mode</P><P>If they run at normal-speed there, an extension is causing your issue normally.<BR />If you use any ad-blocker, script-blocker or page-themer (e.g. Dark Reader) extensions, try setting them to "off" on the pages with an issue and see which is causing the problem</P> Thu, 15 Oct 2026 09:52:50 GMT https://connect.mozilla.org/t5/discussions/firefox-158-is-slow/m-p/143462#M58710 dftf 2026-10-15T09:52:50Z