Comment by ls612

Apollo put a lot more burden on the Service Module than Artemis plans to put on the Orion. Apollo put the CSM/LM into a low lunar orbit while Artemis plans to put Orion into a high lunar orbit and make the Starship carry a lot more delta-V to land from a much higher velocity (and then accelerate back up to that velocity when coming back).

On top of that there weren’t really solar panels in the 1960s so the Service Module had to carry tons of chemicals to produce electricity, as well as extra fuel for all of that weight. As a result it was massively overbuilt compared to anything we’d try today and even so had to take an expedited flight path to the moon of 3 days in order to conserve operational lifetime. Artemis does not have nearly as severe constraints on either the Orion or the future Starship and so can afford to take a more fuel efficient 5 day coast up to the Moon and make the design tradeoffs on Orion that that entails.