It depends a little bit on whether there's a warm container or not, but I think that the overhead is much closer to ~100 milliseconds than to multiple seconds.

It depends a little bit on whether there's a warm container or not, but I think that the overhead is much closer to ~100 milliseconds than to multiple seconds. The CircleCI artifacts API that I linked to takes less than one second to return an artifact, and there's a lot more going on there than a single request/response pair. The endpoint makes an external request to CircleCI's API, does some processing on the response, returns a 301 redirect, and then the redirect is followed by the client and another request is made to actually download the file from S3. You can test this directly by running time curl -L 'https://circleci.intoli.com/artifacts/intoli/exodus/coverage-report/total-coverage.json' which outputs something like the following (the timing will vary a bit obviously). { "coverage": "92.43%" } real 0m0.798s user 0m0.046s sys 0m0.010s