Rails 4：为什么一种更快速渲染局部的方法呢？(Rails 4: why is one way of rendering partials so much faster?)

 我不确定这是否是Rails特定问题，因此我也将其标记为ruby 。 
 
 我通过部分渲染event记录的集合。 但是，我发现不同地呈现部分会导致严重的性能差异。 
 
 两个版本都使用完全相同的数据，唯一改变的是用于渲染部分的代码。 
 
 为什么heck是一个版本始终比另一个版本快4倍？ 让我想知道我正在采取什么样的性能...... 
 
 慢版（950ms总请求时间）： 
 
<% events.each do |event| %>
  <%= render partial: "events/event", locals: { event: event } %>
<% end %>

# Log output
Rendered events/_event.html.erb (1.1ms)
Rendered events/_event.html.erb (1.1ms) 
...
 
 更快的版本（总请求时间250ms）： 
 
<%= render partial: "events/event", collection: events, as: :event %>

# Log output
Rendered events/_event.html.erb (58.7ms)

I'm not sure if this is a Rails specific issue, hence the reason I tagged it ruby as well.
 
I'm rendering a collection of event records via a partial. However, I found that rendering the partial differently results in drastic performance differences.
 
Both version use the exact same data, the only thing changing is the code used to render the partials.
 
Why the heck is one version consistently 4x faster than the other? Makes me wonder what other performance hits I'm taking...
 
Slow version (950ms total request time):
 
<% events.each do |event| %>
  <%= render partial: "events/event", locals: { event: event } %>
<% end %>

# Log output
Rendered events/_event.html.erb (1.1ms)
Rendered events/_event.html.erb (1.1ms) 
...
 
Faster version (250ms total request time):
 
<%= render partial: "events/event", collection: events, as: :event %>

# Log output
Rendered events/_event.html.erb (58.7ms)

原文：https://stackoverflow.com/questions/44509928