Mark H Weaver <mhw@netris.org> writes:

> I've since confirmed that reverting the two upstream commits mentioned
> in <https://bugs.gnu.org/46978> fixes the performance regression.  I've
> attached a preliminary patch for Guix that reverts those upstream
> commits for linux-libre@5.10, and which I've tested on my system.

Here's the patch.

      Mark