100万数据从两个集合寻找不同的值优化

using System;
using System.Collections.Generic;
using System.Data;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace ConsoleApplication3
{
    class Program
    {
        static void Main(string[] args)
        {
            var org_data = "D:\mesdata\原始数据.csv";

            var mes_dataList = OpenCSV(org_data);

            var pis_data = "D:\mesdata\PIS数据2.csv";

            var pis_dataList = OpenCSV(pis_data);
            var dic = new Dictionary<string, string>();

            var list = new List<string>();
            foreach (DataRow item in pis_dataList.Rows)
            {
                list.Add(item[0].ToString());
            }

            DataTable dataTableColor = new DataTable();
            dataTableColor.Columns.Add("SeriesNumber", typeof(string));
            dataTableColor.Columns.Add("Color", typeof(string));

            var mes_dic = new Dictionary<string, string>();
            foreach (DataRow item in mes_dataList.Rows)
            {
                if (!mes_dic.Keys.Contains(item[0].ToString()))
                {
                    mes_dic.Add(item[0].ToString(), item[1].ToString());
                }
            }
            var result=  mes_dic.Keys.Except(list);
            var resultdic = new Dictionary<string, string>();
            foreach (var item in result)
            {
                var color = string.Empty;
                var flag= mes_dic.TryGetValue(item,out color);
                resultdic.Add(item, color);
            }
            foreach (var item in resultdic)
            {
                DataRow dataRow = dataTableColor.NewRow();
                dataRow["SeriesNumber"] = item.Key;
                dataRow["Color"] = item.Value;
                dataTableColor.Rows.Add(dataRow);
            }
            Console.WriteLine("end");
            Console.ReadKey();
        }

        /// <summary>
        /// 将CSV文件的数据读取到DataTable中
        /// </summary>
        /// <param name="fileName">CSV文件路径</param>
        /// <returns>返回读取了CSV数据的DataTable</returns>
        public static DataTable OpenCSV(string filePath)
        {
            Encoding encoding = GetType(filePath); //Encoding.ASCII;//
            DataTable dt = new DataTable();
            FileStream fs = new FileStream(filePath, System.IO.FileMode.Open, System.IO.FileAccess.Read);

            //StreamReader sr = new StreamReader(fs, Encoding.UTF8);
            StreamReader sr = new StreamReader(fs, encoding);
            //string fileContent = sr.ReadToEnd();
            //encoding = sr.CurrentEncoding;
            //记录每次读取的一行记录
            string strLine = "";
            //记录每行记录中的各字段内容
            string[] aryLine = null;
            string[] tableHead = null;
            //标示列数
            int columnCount = 0;
            //标示是否是读取的第一行
            bool IsFirst = true;
            //逐行读取CSV中的数据
            while ((strLine = sr.ReadLine()) != null)
            {
                //strLine = Common.ConvertStringUTF8(strLine, encoding);
                //strLine = Common.ConvertStringUTF8(strLine);

                if (IsFirst == true)
                {
                    tableHead = strLine.Split(',');
                    IsFirst = false;
                    columnCount = tableHead.Length;
                    //创建列
                    for (int i = 0; i < columnCount; i++)
                    {
                        DataColumn dc = new DataColumn(tableHead[i]);
                        dt.Columns.Add(dc);
                    }
                }
                else
                {
                    aryLine = strLine.Split(',');
                    DataRow dr = dt.NewRow();
                    for (int j = 0; j < columnCount; j++)
                    {
                        dr[j] = aryLine[j];
                    }
                    dt.Rows.Add(dr);
                }
            }
            if (aryLine != null && aryLine.Length > 0)
            {
                dt.DefaultView.Sort = tableHead[0] + " " + "asc";
            }

            sr.Close();
            fs.Close();
            return dt;
        }

        public static System.Text.Encoding GetType(string FILE_NAME)
        {
            System.IO.FileStream fs = new System.IO.FileStream(FILE_NAME, System.IO.FileMode.Open,
                System.IO.FileAccess.Read);
            System.Text.Encoding r = GetType(fs);
            fs.Close();
            return r;
        }

        public static System.Text.Encoding GetType(System.IO.FileStream fs)
        {
            byte[] Unicode = new byte[] { 0xFF, 0xFE, 0x41 };
            byte[] UnicodeBIG = new byte[] { 0xFE, 0xFF, 0x00 };
            byte[] UTF8 = new byte[] { 0xEF, 0xBB, 0xBF }; //带BOM
            System.Text.Encoding reVal = System.Text.Encoding.Default;

            System.IO.BinaryReader r = new System.IO.BinaryReader(fs, System.Text.Encoding.Default);
            int i;
            int.TryParse(fs.Length.ToString(), out i);
            byte[] ss = r.ReadBytes(i);
            if (IsUTF8Bytes(ss) || (ss[0] == 0xEF && ss[1] == 0xBB && ss[2] == 0xBF))
            {
                reVal = System.Text.Encoding.UTF8;
            }
            else if (ss[0] == 0xFE && ss[1] == 0xFF && ss[2] == 0x00)
            {
                reVal = System.Text.Encoding.BigEndianUnicode;
            }
            else if (ss[0] == 0xFF && ss[1] == 0xFE && ss[2] == 0x41)
            {
                reVal = System.Text.Encoding.Unicode;
            }
            r.Close();
            return reVal;
        }

        private static bool IsUTF8Bytes(byte[] data)
        {
            int charByteCounter = 1;  //计算当前正分析的字符应还有的字节数
            byte curByte; //当前分析的字节.
            for (int i = 0; i < data.Length; i++)
            {
                curByte = data[i];
                if (charByteCounter == 1)
                {
                    if (curByte >= 0x80)
                    {
                        //判断当前
                        while (((curByte <<= 1) & 0x80) != 0)
                        {
                            charByteCounter++;
                        }
                        //标记位首位若为非0 则至少以2个1开始 如:110XXXXX...........1111110X　
                        if (charByteCounter == 1 || charByteCounter > 6)
                        {
                            return false;
                        }
                    }
                }
                else
                {
                    //若是UTF-8 此时第一位必须为1
                    if ((curByte & 0xC0) != 0x80)
                    {
                        return false;
                    }
                    charByteCounter--;
                }
            }
            if (charByteCounter > 1)
            {
                throw new Exception("非预期的byte格式");
            }
            return true;
        }
    }
}