What’s the size of your print? You need long enough straight-a-ways to gain speed. With small sizes (like a benchy), you’ll never ever get truly high speeds. Too many conflicting accelerations and decelerations stacked one right after the other.
Optimal size may be a large rectangle with large turn radius corners.
Can turn it up to 500+. And yes, my print size in the original was big enough to max out the xy speeds - as it is 12.5in x 12.5in x 12.45ish.