{"action":"closed","issue":{"url":"https://api.github.com/repos/rails/rails/issues/25073","repository_url":"https://api.github.com/repos/rails/rails","labels_url":"https://api.github.com/repos/rails/rails/issues/25073/labels{/name}","comments_url":"https://api.github.com/repos/rails/rails/issues/25073/comments","events_url":"https://api.github.com/repos/rails/rails/issues/25073/events","html_url":"https://github.com/rails/rails/issues/25073","id":155704792,"number":25073,"title":"5.0.0.rc1 weird performance issues","user":{"login":"dreyks","id":1481264,"avatar_url":"https://avatars.githubusercontent.com/u/1481264?v=3","gravatar_id":"","url":"https://api.github.com/users/dreyks","html_url":"https://github.com/dreyks","followers_url":"https://api.github.com/users/dreyks/followers","following_url":"https://api.github.com/users/dreyks/following{/other_user}","gists_url":"https://api.github.com/users/dreyks/gists{/gist_id}","starred_url":"https://api.github.com/users/dreyks/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/dreyks/subscriptions","organizations_url":"https://api.github.com/users/dreyks/orgs","repos_url":"https://api.github.com/users/dreyks/repos","events_url":"https://api.github.com/users/dreyks/events{/privacy}","received_events_url":"https://api.github.com/users/dreyks/received_events","type":"User","site_admin":false},"labels":[{"url":"https://api.github.com/repos/rails/rails/labels/actionpack","name":"actionpack","color":"FFF700"}],"state":"closed","locked":false,"assignee":null,"milestone":null,"comments":7,"created_at":"2016-05-19T10:32:59Z","updated_at":"2016-05-20T14:19:58Z","closed_at":"2016-05-20T14:19:58Z","body":"I may be a little vague, but this is due to not fully understanding where to look. Maybe someone can provide me clues on that.\r\n\r\nI have an app which I slowly move into ~> 5.0 state. Everything is going fine, but upon testing the app in semi-production environment I noticed, that rendering `application.html.erb` takes 30 to 50ms, while on 4.2.6 it takes 3ms. And overall the app is slower.\r\n\r\nTo measure the time I use rack-mini-profiler gem, and the time reported is said to be 'without children duration'.\r\n\r\nSo I began hacking out parts of layout to see where it changes. Assets pipeline was the first to go, but that didn't yield any visible change. After some time I discovered that if I remove all the `render` calls from the layout (but leave the actual `yield` and page content at place), the application.html.erb time actually drops back down to 3ms. \r\n\r\nLet me state this again: rack-mini-profiler reports the time of layout without actual time spent rendering partials, so it looks like something to do with `render` method itself (be it template resolution or whatever).\r\n\r\nAlso, my application consists of several engines (6-7), so the partial lookup paths array is longer than in a usual Rails-app\r\n\r\nAny thoughts?\r\n\r\n### System configuration\r\n**Rails version**: 5.0.0.rc1\r\n\r\n**Ruby version**: 2.3.1\r\n"}}
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