Until you experience the transit from KLIA to KLIA2 it's hard to explain how two 'terminal's that use the same runways can be so far apart especially when it's not traffic that makes the journey slow.

Do note that MH1456 is the last LGK flight of the night from either terminal, i've arrived in KUL very late, so worth making a mental note of your overnight options (i.e. Sama Sama). Malindo also operate about 6 flights a days out of KLIA (they moved from KLIA2 a couple of years ago). I know it's too late now, but handy knowledge for anyone checking this thread in future. Rare to pay more than £40 a sector on them even at short notice, and they do have a business class.