This is not correct. That version of Iris definitely was running correctly until the early builds of Sonoma broke it.
Then you introduced a quick fix that hurt performance by a big margin. I believe it was told at that time that the speed loss would be temporary.
But it persists until now, mainly crippling the (I think) most used 2x upscale.
Even worse:apparently Apple reversed or fixed what they broke in the early Sonoma builds later on as the old model when copied over from a Time Machine archive suddenly did work again.
And even at the time where the bug existed it could be cured by simply starting the app under Rosetta - and, surprisingly this didn’t even have an impact on the speed.
See e.g., but not only my old detailed report here:
