In the Second Prophecy of Mandos (present in most versions of Tolkien's Quenta Silmarillion, but omitted from the final Silmarillion due to a perceived incompatibility by Christopher Tolkien), it's mentioned that Melkor will emerge from the door of night after the world and it's powers grow old and weary (the powers being the Ainur, which includes the Balrogs). This indicates that even the gods will grow old and fade as the elves do, which could imply that Durin's Bane is actually just faded and weakened from age and inactivity, since the balrog was sleeping under the mountain for ~5400 years (assuming it participated in the final battle of the war of wrath and hid itself under Khazad-dûm immediately after Melkor's expulsion). Also, there were no more than 3 or 7 balrogs ever according to later writings by Tolkien, which indicates that no balrog was weak or cowardly.

In regards to Melkor's wailing and summoning of the balrogs: Ungoliant ensnared Melkor in Lammoth, which is described as being near the ruins of Angband where the balrogs awaited Melkor's return. It is said that the balrogs rushed swiftly to Melkor's aid, but there is no indication that the wailing was short. In fact, Lammoth is also known as the land of "the Great Echo" where the wailing of Melkor could still be heard ever after, which to me indicates that the wails were prolonged and intense rather than a swift "yelp" followed by a rescue. With this interpretation, it makes sense to me that the balrogs marched quickly, but still took time to rescue Melkor, which would eliminate the possibility of teleportation or sonic the hedgehog running.

Another interesting writing to note is the involvement of balrogs riding flying fire drakes in the Fall of Gondolin. Now, the Fall of Gondolin is definitely an unfinished tale, and was "neglected" more than the other two great tales/lays of Tolkien's later focus, but there are still consistencies between versions that indicate a certainty of specific elements in Tolkien's mind. In each version, there is mention of balrogs riding to battle atop flying fire drakes to assail the city while orcs and trolls attempt to break the walls. This would indicate to me that balrogs could not fly unaided, which would make any wings they have vestigial (unlikely since they are divine), or more a "cloak" of fire.

The Moria Balrog was just a little baby Balrog who couldn't fly yet.

None of them could go 400 mph. That’s just silly

And completely in keeping with every other facet of fantasy if you want to be that way. A Baalrog can go 400mph just as easily as Gandalf could teleport. All it takes is the stroke of a pen.