The next agi bonus to speed is at 20. You'll see incremental updates until you hit that, then a big bonus (an additional 15%) at that point.
Yes, I still have to adjust agility bonuses, but 17 agi isn't exactly high in the first place
Agi affects attack speed, but not correctly. In the new combat controller, I will have much better control over attack speeds. Right now, attacking is a "spell" and the effect isn't very tunable.