It's really tricky, since your only source for that combination of stats, is through using healing accessories or swapping around casting gear to get a combination of DET, INT, CRT etc while raising or lowering your spell speed. (Spell Speed ><)
Was hoping you would chime in here, since you were using the recording software to measure the difference in frame animation.
I didn't account for Enhanced Pet procing, but I thought I would see a more significant gain than what I did in my quick testing just measuring # of attacks over time. Relying on just recorded attacks, I didn't measure any difference between Base SPD and 721 SPD
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Edited: Did a few more tests, Low Crit with Garuda to try and limit any procs, 10 Trials of 5 mins each.
354 SPD - 100 Hits
731 SPD - 102 Hits
Possibly a ~0.06 increase on cast time. (2% Damage Increase)
Compared to the increase that the SMN should see (+377 SPD = GCD 2.35 or 6% increase in casting speed)
So maybe the pet only sees 1/3 of the gains that the SMN does in regards to SPD.
Still not sure though, because I had 1 run @ 731 SPD of only 100 hits and 1 run @ 354 of 99 Hits. User error could have been an issue, so looking forward to what Chary finds.