Entity Framework中的SaveChanges（）消耗30％的CPU

Question

我需要使用Entity Framework将数据从数据库中的旧表复制到新表中（我在SQL中无法做到），但这非常慢。 如何加快速度？

我检查方法SaveChanges()消耗了30％的CPU-很奇怪。也许不要将相关实体另存为：X.File = userFile-我应该写：X.FileId = userFile.Id？

private void CopyFile(FileFromForm oldFileFromForm)
{
    using (var transaction = _dbContext.Database.BeginTransaction())
    {
        var userSheetsRelatedWithForm = _dbContext.UserRelatedwithForm.AsNoTracking()
                    .Include(x => x.Sheet)
                    .Where(x => x.FormId == oldFileFromForm.FormId)
                    .ToList();

        UserFiles userFile = new UserFiles();
        newCandidateFile.CandidateId = userSheetsRelatedWithForm.First().UserId; 
        newCandidateFile.FileFormatId = 1;
        newCandidateFile.FileTypeId = 2;
        newCandidateFile.CompanyId = oldFileFromForm.CompanyId; 
        newCandidateFile.FileName = oldFileFromForm.FileName;                
        _dbContext.UserFiles.Add(userFile);

        FormFiles formFile = new FormFiles();
        formFile.FormId = oldFileFromForm.FormId;
        formFile.File = userFile; // Can it be: formFile.FileId = userFile.Id ?
        _dbContext.FormFiles.Add(formFile);

        foreach (var sheetId in userSheetsRelatedWithForm.Select(x => x.SheetId).Distinct())
        {
            UserFilesWithSheets userFilesWithSheet = new UserFilesWithSheets();
            userFilesWithSheet.SheetId = sheetId;
            userFilesWithSheet.File = userFile; // Can it be: userFilesWithSheet.FileId = userFile.Id ?
            _dbContext.UserFilesWithSheets.Add(userFilesWithSheet);
        }

        _dbContext.SaveChanges(); // It consumes 30% CPU !!!
        transaction.Commit();
    }
}