C#海量SQL更新查询

我有一个180万行文本文件,我需要注入一个SQL表,我的代码工作正常,只是有点慢(如每天250k行).不幸的是,我有大约4个这样大小的文本文件,所以我需要一种方法来加快这个过程.任何帮助,将不胜感激.如果某些代码看起来不正确,那么我会省略一些隐私的东西.我知道我可以砍掉file.appendall,但我用它来跟踪它,我也做了明星,所以我可以在第二天拿起来不停止备份.

DirectoryInfo dinfo = new DirectoryInfo(ocrdirectory);
FileInfo[] Files = dinfo.GetFiles("*.txt");
foreach (FileInfo filex in Files)
{
        string[] primaryfix = File.ReadAllLines(dinfo + "" + filex);
        string filename = filex.ToString();
        string[] spltifilename = filename.Split('.');
        foreach (string primary in primaryfix)
        {
            string sqltable = ("dbo.amu_Textloadingarea");
            string sql = "update " + sqltable + 
                         " set [Text] = [Text] + '" + primary +"|"+ 
                         "' where unique = '" + spltifilename[0] + "'";
            File.AppendAllText(@"C:convertsqltest.txt",sql+"n");
            SqlConnection con = new SqlConnection("Data Source= Cote ;Initial Catalog= eCASE;Integrated Security= SSPI");
            con.Open();
            SqlCommand cmd = new SqlCommand(sql,con);
            SqlDataReader reader = cmd.ExecuteReader();
            con.Close();
            Console.WriteLine(start);
            start++;
        }