I think there are many more things a LCC could save on if you compare to CX/KA.
A pure LCC would not have a big expensive office. FF programs are expensive for the airline but sometimes the program in its self makes money. If you only sell tickets on Internet you save 5-8 percent compared to sell them thru travel agents. No F/J class makes catering more efficient. All these small things will make a lot of money added together. Look at Ryan Air. CX is not even close to them.