> if they control everything and can drop a standard 90ms down to 10ms
10ms, after request processing, ad selection logic, and faster-than-light packet travel? I think that's far too optimistic of an improvement. As the post said, 30ms was the goal. My adserver delivers in 20-40ms. But since ads are routinely loaded asynchronously, is speed concern truly valid? The adserver can usually make a selection and deliver before the content is fully rendered in the browser.
> Talking from the experience of building out a system that handled +1B impressions a day, the actual ad serving isn't challenging at all these days.
If you developed a system that delivers 1BB impressions per day (most large scale ad networks deliver only a modest multiple of that number) and didn't find it challenging, then it's either a very simple system or you're Elon Musk ;) That's 12k requests per second, generally uncached, hitting all sorts of internal services most likely.
I'm just saying that I think Reddit's best bet is to offload the task to a company that works on these problems full time. Or acquire one like AOL and Facebook. Unless the use cases are so unique and key to the company's future plans, avoid building in-house. And if you have to, perhaps it would be a larger effort than a 3 person team developing the thing in a language that the company never used in production before.