The answer is: it depends.

Military Dragons have, of course, many shapes and sizes. Some (like the Dragons of Pern, or less obviously the dragons of His Majesty or those of Harry Potter) have such serious differences in weight and general silhouette that their speed will always be impacted by their general class. Green and Blue Pernese Dragons, for example, tend to be faster in short bursts and more manageable in tight turns than their Brown or Bronze counterparts and would have no trouble carrying a coconut at least as fast as an unladen European swallow. (Although stamina is another issue again, of course). Toothless, the Dragon that was trained by the Viking Hiccup, can literally break the speed of sound in a dive, and would have no trouble carrying a coconut beyond that limit.

On the other hand there are dragons which would have tremendous difficultly in even carrying the coconut. The Oriental dragon released in book two of the Last Dragonlord series objectively has legs with claws too short and broad to grasp the coconut adequately. That last mentioned Dragon being aquatic does, of course, reduce its speed in air considerably (down to just flopping about).

I am afraid you must bound your question in much stricter terms than this to get a coherent answer.

For our flaired users here, can you perhaps being more specific in your question?

African or European?