So I don’t know if your experience is the same as mine was, but I played XIV on a gaming laptop with a 4gb gtx 960m, 8gb ram, and 2.3 quadcore for a couple of years. Running both Miqo and XIV pretty much kept my system performance running at max capacity. When Miqo was updated for ShB, she wouldn’t hit 6 GCD’s, always only hitting 5. I just figured that until she was optimized to hit Wildfire after Hypercharge like the Balance openers showed, she would always hit 5. But since upgrading to a desktop with a GTX 1080, 16gb ram, and 3.7 quadcore, the whole game runs butter smooth, and on top of that little rotational issues I had across the board for all job rotations with miqo are no longer present. Miqo hits 6 GCD’s in the Wildfire window even with pressing it before Hypercharge. She hits 5x Heatblasts and then will go for the first step int he three-shot rotation because she doesn’t anticipate Drill being off CD by the time the 5th HC is done casting, so I manually press Drill, but even then I have plenty of time to get Drill in before WF ends. So I wonder if maybe your system is being strained?
If you’re running a nice system and the game plays butter smooth even with Miqo running, then I don’t know what the issue could be.
TL;DR yes it’s possible for Miqo to hit 6 GCD’s in WIldfire because she does it for me with no issues (now.)