加入4个MySQL时LINQ运行缓慢

Question

我试图弄清楚为什么在C＃中使用Linq将4个表连接在一起时速度很慢。此外，有两个相同的表wp_posts。我想知道我是否可以减少表格，它可能会更快。我正在使用MySQL。

var results = from a in _newsEntities.wp_posts
            join b in _newsEntities.wp_postmeta
            on a.ID equals b.post_id
            join c in _newsEntities.wp_posts
            on b.meta_value equals c.ID.ToString()
            join d in _newsEntities.wp_users on a.post_author equals d.ID
            where a.post_status == "publish" &&
                  a.post_type == "post" &&
                  b.meta_key == "reporter_name"
            select new
            {
                Id = a.ID,
                Status = a.post_status,
                Content = a.post_content,
                ReporterId = c.post_content,
                ReporterName = c.post_title,
                DateCreated = a.post_date,
                DateModified = a.post_modified,
                AuthorId = a.post_author,
                AuthorName = d.display_name
            };