Art at ISP
Veteran
I have heard from some Airbus pilots that the A-321 is somewhat underpowered, and it sometimes has problems climbing to an efficient cruise altitude with full fuel and load. Some transcons start out very low, cruising in the 20's for a while before being light enough to get to FL310 or higher. Similar flights on the same days in 319's or 320's are as high as FL350 by that time (according to Flight Explorer).
Therefore I think BOS is a performance issue as well.
Therefore I think BOS is a performance issue as well.