linq - linq to sql クエリの最適化の提案が必要

Question

最初に私はこのクエリを書きました

var lst = (from mediaref in MediaRefs
               join media in Medias 
               on mediaref.Int_MediaId equals media.Int_MediaId
               join mediatype in MediaTypes
               on media.Int_MediaTypeId equals mediatype.Int_MediaTypeId
               where mediatype.Int_MediaTypeId_FK == 1 
                   && mediaref.Bit_IsActive == true
                   && media.Int_OrganizationId == 2
                   && media.Int_PostStatusId != 3 
                   && mediaref.Int_MediaRefId == mediaref.Media.
               MediaRefs.FirstOrDefault(m => m.Int_MediaId == media.Int_MediaId 
               && m.Bit_IsActive == true &&
               (m.Nvcr_MediaTitle != null 
               && m.Nvcr_MediaTitle != "")).Int_MediaRefId
               orderby media.Int_MediaId descending

               select new MediaViewModel {
                  MediaId = media.Int_MediaId,
                  Mediatitle = mediaref.Nvcr_MediaTitle ,
                  Mediapath = mediaref.Vcr_MediaPath,
                  Slug = mediaref.Vcr_Slug,
                  Active = mediaref.Bit_IsActive
                });

その後、これに変更

var lst = (from mediaref in MediaRefs
               join media in Medias 
               on mediaref.Int_MediaId equals media.Int_MediaId
               join mediatype in MediaTypes on
               media.Int_MediaTypeId equals mediatype.Int_MediaTypeId
               where mediatype.Int_MediaTypeId_FK == 1 
                     && mediaref.Bit_IsActive == true
                     && media.Int_OrganizationId == 2 
                     && media.Int_PostStatusId != 3 
                     && mediaref.Nvcr_MediaTitle != ""                         
               group new {mediaref, Medias, MediaTypes} by new {
                     media.Int_MediaId,                         
                     mediaref.Vcr_MediaPath,
                     mediaref.Vcr_Slug,
                     mediaref.Bit_IsActive                       
                }  into g
                      orderby  g.Key.Int_MediaId descending

                select new MediaViewModel {
                  MediaId = Convert.ToInt64(g.Key.Int_MediaId),
                  Mediatitle = g.Min(p => p.mediaref.Nvcr_MediaTitle) == "" ? 
                         g.Max(p => p.mediaref.Nvcr_MediaTitle) : 
                         g.Min(p => p.mediaref.Nvcr_MediaTitle),
                  Mediapath = g.Key.Vcr_MediaPath,
                  Slug = g.Key.Vcr_Slug,
                  Active = g.Key.Bit_IsActive
                });

このクエリは、もう少し効率的な方法で記述できますか? media問題は、最初の行に参加したいということmediarefですmedia. 助言がありますか。この最初のクエリで使用したものFirstOrDefaultと、2 番目のクエリで使用したものgroup byです。