Bringing 5+ quarts of water to a boil takes a lot of energy. Hell, it takes my jetboil 90s-120s to boil low-temp water in like...1 quart quantities. It doesn't seem unreasonable to me that a large pot of water takes 8-10 minutes to bring to a rolling boil.
More than a gallon? That's a big batch of spaghetti - it stands to reason that if you're feeding a great multitude, there's going to be a cost in cooking fuel.
Right. And in fact, it's better that way. There's more starch in the water, which makes it more useful when you add some to the sauce in your sauce pan.
What, you don't finish your pasta by heating it with the sauce??? Hang your head in shame.
no. they shamelessly pan fry pasta. (and rinse them briefly with fresh water to get rid of the starch and stop the cooking for bite. also works just perfect with a low amount of water)