* Carbon dioxide makes water slightly acidic. This can slightly enhance the dissolving of some substances, but it's not a dramatic effect.

* The bubbles themselves don't directly help dissolve sugar. The bubbles are simply carbon dioxide gas, and they don't interact with the sugar in a way that would make it dissolve faster.

* The agitation from the bubbles might have a minor effect. The rising and popping of bubbles can cause a small amount of stirring, which could slightly speed up the dissolving process. However, this effect is likely very small compared to proper stirring.

In conclusion: While carbonated water might have a tiny edge over plain water in terms of sugar dissolving speed due to its slight acidity and the minimal agitation from bubbles, the difference is likely insignificant. The primary factor influencing sugar dissolving speed is stirring or shaking.