https://connect.mozilla.org/t5/discussions/update-to-firefox-esr-140-13-0-w11-very-bad-performance/m-p/132710#M53201 <P>This is my first post, so apologies if this should be notified elsewhere, but it was bad enough that I thought I should mention it somewhere.</P><P>Two days ago I allowed the update to 140.13.0esr, from 140.12.0esr, (en-GB edition).<BR />On Windows 11 25H2 updated.<BR />I then noticed a number of things were generally less responsive, it was as if FF was waiting 0.5-2 seconds before actually taking effect. From selecting another tab, menu selection, typing, pages responding (controls on a page etc), slow loads.&nbsp;<BR />I do have VERY MANY windows &amp; tabs, initially I though I had hit some limit, so close a good number, no difference.&nbsp;<BR />Restarted.<BR />Blamed some sited I had not visited before.<BR />Looked at Process Manager [where I'm no expert) (some of the above sites were high CPU for many seconds),<BR />Unfortunately I did not keep the results, but there were plenty of Red &amp; Black lines at the top, and a LOT of GC.</P><P>It was so bad I had to downgrade, and it is back to normal.</P><P>There is something seriously wrong with 140.13.0<BR />This is not a specific bug, so I didn't think Bugzilla was appropriate.</P><DIV class="">&nbsp;</DIV><DIV class="">Edit oops fixed 140.13/12 not 140.0.nn Dyslectic.</DIV> Sat, 25 Jul 2026 04:28:35 GMT MichaelAtOz 2026-07-25T04:28:35Z https://connect.mozilla.org/t5/discussions/update-to-firefox-esr-140-13-0-w11-very-bad-performance/m-p/132710#M53201 <P>This is my first post, so apologies if this should be notified elsewhere, but it was bad enough that I thought I should mention it somewhere.</P><P>Two days ago I allowed the update to 140.13.0esr, from 140.12.0esr, (en-GB edition).<BR />On Windows 11 25H2 updated.<BR />I then noticed a number of things were generally less responsive, it was as if FF was waiting 0.5-2 seconds before actually taking effect. From selecting another tab, menu selection, typing, pages responding (controls on a page etc), slow loads.&nbsp;<BR />I do have VERY MANY windows &amp; tabs, initially I though I had hit some limit, so close a good number, no difference.&nbsp;<BR />Restarted.<BR />Blamed some sited I had not visited before.<BR />Looked at Process Manager [where I'm no expert) (some of the above sites were high CPU for many seconds),<BR />Unfortunately I did not keep the results, but there were plenty of Red &amp; Black lines at the top, and a LOT of GC.</P><P>It was so bad I had to downgrade, and it is back to normal.</P><P>There is something seriously wrong with 140.13.0<BR />This is not a specific bug, so I didn't think Bugzilla was appropriate.</P><DIV class="">&nbsp;</DIV><DIV class="">Edit oops fixed 140.13/12 not 140.0.nn Dyslectic.</DIV> Sat, 25 Jul 2026 04:28:35 GMT https://connect.mozilla.org/t5/discussions/update-to-firefox-esr-140-13-0-w11-very-bad-performance/m-p/132710#M53201 MichaelAtOz 2026-07-25T04:28:35Z