I'm in the same boat: I defected from 4e to Pathfinder, but as much as I've loved Paizo, Pathfinder is a headache to run.
The big thing to realize is that in 3.x/PF, characters got taller: there numbers got larger and larger. AC, saves, skills, attacks, spell DCs, etc all got huge. My PF group is 6th level, and hitting AC 30+ is not uncommon. 5e gets wider: ACs, saves, skills, etc don't get as big, but you gain more options. Once you adjust to this, the game feels smoother and less stepped than PF.
Another thing: Magic item math isn't assumed so you don't need to keep trading in weak or un-wanted stuff for better plussed weapons, armor, cloaks, rings, and stat boosters.