PERF: Partially recover some performance when preloading.

Benchmark Script:
```
require 'active_record'
require 'benchmark/ips'

ActiveRecord::Base.establish_connection(ENV.fetch('DATABASE_URL'))
ActiveRecord::Migration.verbose = false

ActiveRecord::Schema.define do
  create_table :users, force: true do |t|
    t.string :name, :email
    t.integer :topic_id
    t.timestamps null: false
  end

  create_table :topics, force: true do |t|
    t.string :title
    t.timestamps null: false
  end
end

attributes = {
  name: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit.',
  email: 'foobar@email.com'
}

class Topic < ActiveRecord::Base
  has_many :users
end

class User < ActiveRecord::Base
  belongs_to :topic
end

100.times do
  User.create!(attributes)
end

users = User.first(50)

Topic.create!(title: 'This is a topic', users: users)

Benchmark.ips do |x|
  x.config(time: 10, warmup: 5)

  x.report("preload") do
    User.includes(:topic).all.to_a
  end
end
```

Before:
```
Calculating -------------------------------------
             preload    40.000  i/100ms
-------------------------------------------------
             preload    407.962  (± 1.5%) i/s -      4.080k
```

After:
```
alculating -------------------------------------
             preload    43.000  i/100ms
-------------------------------------------------
             preload    427.567  (± 1.6%) i/s -      4.300k
```

0 files changed, 0 insertions, 0 deletions