Because I choose to save the pictures in the database I saw that when you query the Pictures entity (even when checking only for IsNew) every time you get from the DB the PictureBinary which is very heavy and makes the query run slow.
What I have done to pass this issue:
I have split the Picture entity in 2 entities: Picture(PictureId,Extension,IsNew) and PictureFullIamge(PictureId, PictureBinary) and making use of PictureFullIamge only when is needed.
paliktar