First off I have to say that heat doesn't exactly ignore durability like some people in this thread think...But anyway, how fast is Zebra? Well honestly, the mounturtle fight is what will explain that, also he has another speed feat that I'll go over.
Ok to begin with, as you can see here
His beams are pretty damn fast, and even if they weren't, the explosion is huge enough to wipe out an entire army, for further scope of his firepower, the mounturtle was also able to blow an ice continent to pieces. Yet as you saw in Othus's scan, Zebra was much too fast for the mounturtle even though it was spamming such ridiculous firepower, pretty easily I might add. Also as for Zebra's firepower, well, you saw in the scans above that even with an advanced futuristic army, with enough raw firepower to blow away 10 million square kilometers off the map (don't forget satellite frickin lasers), it didn't do jack, but against Zebra? Well...
Ok, pretty impressive right, well, here's something else, each of the heavenly kings has a pet that is faster in movement speed than they are, however, the kings have reactions fast enough to perceive things happening around them while they ride them. How fast are the pets? Well, http://www.narutoforums.com/blog.php?b=17700
That explains it well enough there, going even with the lowest end possible, its much faster than anything in bleach, but likely, it took their pets less than a few minutes to reach the center of human world from the outskirts (human world in Toriko is friggin huge) considering the situation that was taking place there, Zebra's pet was also faster than the others by the way. Also they can leap on top of their pets after the pets have broken into a run already. But, as for an actual scan of speed, I can also provide that
Ok lets get started
Zebra travels across an entire city in no time to deliver a punch to the 4 beast, who is extremely fast himself. Keep in mind that this city is so huge it can easily contain hundreds of millions of people, the number that was there at the time was 500 million, it's a big ass city, everything in Toriko is huge if you didnt notice lol. This is a bit unrelated but they took a beating from the 4 beast for an hour while poisoned and slowly dying, just stating that to show how durable Zebra and the kings are, btw, 4 beast is made up of 4 powerful creatures it absorbed, including mounturtle and other creatures just as strong as it, so, its pretty fuckin strong.
Anyhow, here's probably his most clear cut speed feat shown so far
Here the kings are, beaten to near death while poisoned, about to be flattened by the 4 beast, and this is what Zebra does
He uses his jet voice to instantly transport the 4 kings to other side of the friggin city, he did this without them knowing by the way, as in he moved them (yes he can do that, he recently did it to 100 million people at once and moved them to a distant island from where he was). Hope this helps you understand Zebra a bit more, by the way I highly recommend reading Toriko, rather than watching the anime, it's imo a fun series, one of my favorites ever.
EDIT: The current calc's for the kings puts them at around mach 700+ with higher reaction times than their actual speed, for Coco even more so due to his enhanced vision