How to optimise the code

How would I optimize the following code?

def posts_for_30_blogs
  blogs = Blog.limit(30)
  blogs.flat_map do |blog|
    blog.posts.to_a
  end
end

Optimise in what sense? If this is about solving the N + 1 query problem
then try:

blogs = Blog.include(:posts).limit(30)

This should load associated posts with only 1 query.

Thanks very much..