It seems that your argument throughout this discussion is based on two assumptions.
(1) Software already has acceptable performance.
(2) Further work to improve its performance is likely to have large development costs but deliver only small benefits.
I’m not sure either of those assumptions is safe. As the early parts of the lecture we’re discussing today demonstrated, sometimes there are dramatic performance improvements that can be made if you know what you’re doing and they can make a similarly dramatic difference to how beneficial the software is to its users.
(1) Software already has acceptable performance.
(2) Further work to improve its performance is likely to have large development costs but deliver only small benefits.
I’m not sure either of those assumptions is safe. As the early parts of the lecture we’re discussing today demonstrated, sometimes there are dramatic performance improvements that can be made if you know what you’re doing and they can make a similarly dramatic difference to how beneficial the software is to its users.