{"action":"opened","issue":{"url":"https://api.github.com/repos/systemjs/builder/issues/592","repository_url":"https://api.github.com/repos/systemjs/builder","labels_url":"https://api.github.com/repos/systemjs/builder/issues/592/labels{/name}","comments_url":"https://api.github.com/repos/systemjs/builder/issues/592/comments","events_url":"https://api.github.com/repos/systemjs/builder/issues/592/events","html_url":"https://github.com/systemjs/builder/issues/592","id":154886049,"number":592,"title":"Fetch override performance","user":{"login":"bmayen","id":326325,"avatar_url":"https://avatars.githubusercontent.com/u/326325?v=3","gravatar_id":"","url":"https://api.github.com/users/bmayen","html_url":"https://github.com/bmayen","followers_url":"https://api.github.com/users/bmayen/followers","following_url":"https://api.github.com/users/bmayen/following{/other_user}","gists_url":"https://api.github.com/users/bmayen/gists{/gist_id}","starred_url":"https://api.github.com/users/bmayen/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/bmayen/subscriptions","organizations_url":"https://api.github.com/users/bmayen/orgs","repos_url":"https://api.github.com/users/bmayen/repos","events_url":"https://api.github.com/users/bmayen/events{/privacy}","received_events_url":"https://api.github.com/users/bmayen/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"milestone":null,"comments":0,"created_at":"2016-05-15T02:16:19Z","updated_at":"2016-05-15T02:16:19Z","closed_at":null,"body":"According to the docs, fetch override should return a string. The example shows a fallback to return a Promise though. Following this example works, but it suffers a ~1s performance hit. Even if all I do is `return fetch(load)`, it's roughly 1s slower than if I don't override at all. Testing this with a very small dependency tree (3 files). Not sure if the hit is significantly more with more files. \r\n"}}