Here’s one way I discovered, quite by accident, to decrease the amount of time it takes to cook quince to about less than half:

freeze them!

Yes, by freezing sliced quince, the water inside the cells and membranes burst, imparting tenderness to the fruit once it thaws. This way, I found that a mere 25-30 min gentle simmer on a shallow pan will cook them and still maintain excellent firmness and flavour.