I personally find leveling to be extremely fast in this game. That is, if you know what to do at each level.

LVL 80 to 90 became fast after the EXP boost to Endwalker dungeons. I already got 8 jobs (9 if you count SCH/SMN separately) to 90 after the EXP boost. Getting Reaper from 70 to 90 wasn't bad either. Leveling 80 to 90 will become even faster once we get PoTD Endwalker edition.