Feels like BLU is lvling really slow after 60 - normal or I'm doing something wrong?

I've leveled BLU in the open world since lv1 and it's been just fine so far. Taking on a few levels above my own, making use of the combo meter, and so on.

It just feels like ever since I moved to mobs above 60 the leveling has slowed down drastically, and not just by a margin I'd expect as levels get higher. When mobs took 3-4 hits in the 50s, they're now taking 10-20 hits depending on what combo I have on cooldown.

For context I'm currently
- Level 62
- Fully decked in Shire gear
- Fighting level 67 at Yanxia
- Using a combo of Whistle > Tingle > Triple Trident whenever I can, then moving to spam single target spell and occasional instant cast Eruption

The combo doesn't even do half HP dmg, so each mob takes a while and provides only around 50k XP out of the 1.5M needed for level. I know that's just 30 mobs, but still feels like so much longer than before. If there's some tricks I'm missing out on I'm all ears, else if this is just normal and 60-80 is intended to be a longer trek so be it. Just figured I'd come ask and find out for sure.

I thought about trying to mix in
- Whistle > Tingle > Bomb Toss > Sharpened Knife

but the timing is tricky XD

Do you have more spells than this? There's a lot of extra DPS tools you could be learning at level 60 and below. You should also use your companion chocobo whenever possible, for added support.
I recommend getting the following spells:

• Choco Meteor from overworld Courser Chocobo mobs in the Dravanian Forelands - I was just about to edit this into my comment, but Absurdity also mentioned it first. It's an extra-powerful AoE spell as long as you have your companion chocobo summoned.
• Missile from Battle in the Big Keep - Reduces enemy health by 50% if they are not above your level. Cuts the time it takes to kill enemies in... half, I guess.
• Launcher from Baelsar's Wall boss 2 - It's like Missile, but an AoE.
• The Ram's Voice from Cutter's Cry and Ultravibration from the overworld Kongamato mob in The Peaks - Using the spells in a combo instantly kills regular mobs if they aren't above your level.
• More primal OGCD spells, especially Shock Strike and Surpanakha. Many can be used in quick succession to wipe the floor with regular mobs.
• Song of Torment from Pharos Sirius is a powerful DoT when combined with Bristle - You will also get Sonic Boom from this duty if you don't have it already, a strong regular attack.

Of course, many of these spells only work on mobs that aren't above your level, but I actually found it a worthwhile tradeoff for how fast you can kill them. Or at least, this is how I did levels 70 to 80.

I'd recommend getting Choco Meteor from the Courser Chocobo in the Dravanian Forelands, probably the best filler spell you can get for open world leveling. 300 AoE potency while you have your chocobo companion.
And as Picothea already said, once you get to The Peaks you can grab Ultravibration from Kongamato. 2 minute cooldown and oneshots every frozen enemy.

Of course there are also a bunch more good oGCDs.
Feather Rain from Garuda, Shock Strike from Ramuh, Glass Dance from Shiva, J Kick from Brute Justice, Surpanakha from Ravanah and later Both Ends from the monkey boss in Swallow's Compass.

Hydro Pull from the Kelpi in Drowned City of Skalla might also be worth getting for pulling in enemies and grouping them up.

I do have some of those, and the Ultra Vibration combo with Ram's Voice was something I looked at but didn't go with due to its 2min cooldown plus how you need to always be against mobs equal level to you (or below and lose some XP proficiency). I might try this out though for 70-80, it's a good point that the speed might make up for the XP dimished. I'll certainly look into the other primal spells, I was avoiding BLU spells from dungeons just because mostly I've been leveling BLU while my DPS waits for its queue, but I suppose it's time to actually put some focused time into BLU now.

Funnily enough I have Choco Meteor and just wasn't using it XD silly me, I always have my choco out in the open world so I was using a 200 potency spell instead of 300 for nothing O.o that's a good one

Thanks for the insights :) I'll head back to the grind

I found fastest leveling for me was to simply kill mobs on level and keep racking up the combo bonus. Higher and lower leveled mobs didn't really do anything compared to on level. I stayed away from Fates since the mobs there are always below the level of the fates so either you get too little Xp from mobs or don't get full contribution and rewards from the Fate.

Generally the best leveling for BLU I found was to gather up as many enemies together as possible, using Healer Aetheric Mimicry and Mighty Guard to stay alive, then hit them with the Ram's Breath and Ultravibration combo. The two minute cooldown is an annoyance, but if you're killing mobs at your level or above you do get the chain bonuses which does contribute a decent amount.