I currently load cast for 3 9mm firearms. A Custom made stub barrel for my Handi Rifle single shot. A Hipoint C9 pistol, and a Hipoint 9mm Carbine. (and another in .40sw)
Just like everything else, bullet fit is king.
When you get the bullet big enough yet it will chamber then you start playing with the other variables.
Mine tend to be mostly loaded with Red Dot, from 3 grains to 4.5 depending on which gun they are intended for. They are loaded up in 100 round MTM boxes and the load is on the box.
In the case of my Hipoint C9 pistol cast .3595-.360 lead was more accurate than Federal FMJ factory loads by at least an inch at 20 feet.
But I will admit I don't always push for max speed either.
The 4-4.5 gr loads of Red Dot are quite comfortable in the Hipoint Carbine or the single shot. But are a bit snappy for my taste in the pistol.
Why make my own ammo if I can not adjust it so that it makes a perfect fit to my needs.
I tend not to chase the whole speed thing. That's a young man's game.
I do like perfect function without issues, and accuracy is always nice.
And it has been my experience that true accuracy and speed seldom go hand in hand.
More like opposite ends of the teeter totter. You raise one you lower the other.
Its all about balance, and where you are sitting on the board.