[jonathanoliver]

On AWS booting Windows can easily take 10-15 minutes. On the same type of EC2 instance, it takes 30 seconds. This makes auto scaling quickly very difficult because you have to scale up in anticipation of demand rather than as it occurs.

One other problem is that Windows by itself easily takes 1+ GB of RAM whereas Linux can easily run 64MB-128MB. So while Windows may only be 20% more expensive for similar hardware (which I don't object to either), I can run cheaper hardware and have more of it available to the application instead of the OS. Our metrics show the savings to be about 60% less expensive when counting hardware and licensing costs.

[DenisM]

The boot time is annoyance, and resource hogging is unfortunate, but I can easily buy my way out of those problems by buying bigger machines and doing it in advance. My time is more valuable, I think, and server costs are negligible next to payroll. There are business models where hardware costs dominate like, I don't know, video processing or something, but most startups are not in that boat - they need to iterate on UX as fast as possible.