There's already a lot of negativity on this thread, suggesting that they only care about this because they're facing bad PR and lawsuits. I'm inclined to give

There's already a lot of negativity on this thread, suggesting that they only care about this because they're facing bad PR and lawsuits. I'm inclined to give them the benefit of the doubt. They made a reasonable engineering and product tradeoff to increase their system's scalability, decrease it's latency, and allow new kinds of applications that are able to serve more than one request at once (eg. node.js servers holding onto tons of idle websockets). Given an increasingly large infrastructure (which makes stronger queueing much harder if you don't want to add a lot of latency) and strong requests from customers to allow other languages that don't fit into the "one fast request per process" paradigm, I can absolutely see making that tradeoff. It makes the infrastructure simpler (and thus more robust), cuts some latency, and makes the many loud customers who wanted to run things like node.js happy. Doing so, I would have been aware that in some cases, this would lead to suboptimal routing that increased latency, but I never really would have thought it would have as devastating effects on an application's overall performance as Rap Genius saw. So yes, they do care a lot more about this issue now that there has been a big stir about it, but I think it's reasonable to assume that this may be more because they've realized it can have a huge impact on overall latency rather than a moderate one, and that it's come to their attention that some of their messaging and docs hadn't been updated reflecting the routing change. But given how great of a company Heroku usually is, the fact that it is not in their interest to decrease their quality of service, and that there are very legitimate reasons to move away from intelligent routing (namely, the facts that it doesn't really make sense for applications that can do multiple requests concurrently and that it is extremely difficult to scale), I'm inclined to believe that this is more a mistake than a malicious lack of concern for their customer's well-being that they are only addressing due to vocal outside pressure.