I have three models that look something like this:

class Bucket < ActiveRecord::Base
  has_many :entries
end

class Entry < ActiveRecord::Base
  belongs_to :submission
  belongs_to :bucket
end

class Submission < ActiveRecord::Base
  has_many :entries
  belongs_to :user
end

class User < ActiveRecord::Base
   has_many :submissions
end

When I retrieve a collection of entries doing something like:

@entries = Entry.find(:all,
                      :conditions => ['entries.bucket_id = ?', @bucket],
                      :include    => :submission)

The performance is pretty quick although I get a large number of extra queries because the view uses the Submission.user object. However, if I add the user to the :include statement, the performance becomes terrible and it takes over a minute to return a total of 50 entries and submissions spread across 5 users. When I run the associated SQL commands, they complete in well under a second.

@entries = Entry.find(:all,
                      :conditions => ['entries.bucket_id = ?', @bucket],
                      :include    => {:submission => :user})

Why would this second command have such terrible performance compared to the first?