it takes about the same amount of time as getting from L1 to L50. If you are not trying to just grind it out in one day, you can:
benefit from a bonus 400k xp each day from inspiration (from L50 onwards), if you get at least 100k xp
do a daily premium random dungeon, for 100k xp (scaled if below cp160) for completion of your first random dungeon run of each day via group finder
do a daily premium random Battleground for 100k xp (scaled if below cp160) for finishing in the first or second team in a random battleground. (If your team finishes third, just do another random BG until your team is NOT third). Plus Alliance points, which count double in the current event, if you do the miniquest in Cyro to get a Pelinal scroll (and use it) first.
These three things make it super easy to get xp fast with not too much time spent each day. You can grind out more xp if you have more time of course.
Seems to be a regular dolmen farming group running in the Alkir Desert non stop ever day all day but I couldn't think of a more boring way to level personally.
that´s probably the most entertaining way. Do dungeons as a healer. Don´t forget the learning gear and the xp scrolls.
Should only take a couple of hours this way.