<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta content="width=device-width, initial-scale=1.0" name="viewport" />
    <meta name="apple-mobile-web-app-capable" content="yes" />
    <meta name="mobile-web-app-capable" content="yes" />
    <meta name="apple-mobile-web-app-status-bar-style" content="black-translucent" />
    <meta name="theme-color" content="#5288ff" />
    <meta name='author' content='אביב לוינסקי' />
    <title>Private Events</title>
    <%= stylesheet_link_tag 'application',
                            '//fonts.googleapis.com/css?family=Roboto:400,500,600',
                            media: 'all',
                            'data-turbolinks-track' => true %>
    <%= javascript_include_tag 'application', 'data-turbolinks-track' => true %>
    <%= csrf_meta_tags %>
    <%= render 'layouts/shim' %>
  </head>

  <body>
    <%= render 'layouts/header' %>

    <% if flash.present? %>
      <div class="container">
        <% flash.each do |type, msg| %>
          <%= content_tag(:div, msg, class: "alert alert-#{type}") %>
        <% end %>
      </div>
    <% end %>

    <%= yield %>

    <%= render 'layouts/footer' %>
    <%# debug(params) if Rails.env.development? %>
  </body>
</html>

<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta content="width=device-width, initial-scale=1.0" name="viewport" />
    <meta name="apple-mobile-web-app-capable" content="yes" />
    <meta name="mobile-web-app-capable" content="yes" />
    <meta name="apple-mobile-web-app-status-bar-style" content="black-translucent" />
    <meta name="theme-color" content="#5288ff" />
    <meta name='author' content='אביב לוינסקי' />
    <title>Private Events</title>
    <%= stylesheet_link_tag 'application',
                            '//fonts.googleapis.com/css?family=Roboto:400,500,600',
                            media: 'all',
                            'data-turbolinks-track' => true %>
    <%= javascript_include_tag 'application', async: Rails.env.production?, 'data-turbolinks-track' => true %>
    <%= csrf_meta_tags %>
    <%= render 'layouts/shim' %>
  </head>

  <body>
    <%= render 'layouts/header' %>

    <% if flash.present? %>
      <div class="container">
        <% flash.each do |type, msg| %>
          <%= content_tag(:div, msg, class: "alert alert-#{type}") %>
        <% end %>
      </div>
    <% end %>

    <%= yield %>

    <%= render 'layouts/footer' %>
    <%# debug(params) if Rails.env.development? %>
  </body>
</html>

Use js async loading - trial
Use js async loading - trial
