Some big factors for pans performing well. 1) The arch design, is it a high efficiency arch, airtight and insulated on the door, air under the fire, grate styled for air. 2) Is it a high output pan, additional flues, maybe a hood. Both companies mentioned here offer these set ups. I personally boil on one of these and it boils at the rate I expect with the pan and arch I have. If you preheat your syrup before it comes into your pan that increases the boiling rate too. Look up which pan it is and you can get these answers.