As you say, we don't (founder of https://circleci.com https://circleci.com here). Our infrastructure runs on LXC, so we divide up big EC2 machines into about 10

As you say, we don't (founder of https://circleci.com https://circleci.com here). Our infrastructure runs on LXC, so we divide up big EC2 machines into about 10-12 containers, and of course it's multi-tenant so if you're not pushing code you're not costing us money.