Test file for speedup of saving 0.100 vs 0.101

gistfile1.txt

using System;
using System.Data;
using System.Diagnostics;
using ClosedXML.Excel;

namespace ClosedXML.Sandbox
{
    internal static class Program
    {
        private static void Main(string[] args)
        {
            DataTable dt = new DataTable();
            DataColumn dc1 = new DataColumn("A", typeof(String));
            DataColumn dc2 = new DataColumn("B", typeof(String));
            DataColumn dc3 = new DataColumn("C", typeof(String));
            DataColumn dc4 = new DataColumn("D", typeof(String));
            DataColumn dc5 = new DataColumn("E", typeof(String));
            DataColumn dc6 = new DataColumn("F", typeof(String));
            DataColumn dc7 = new DataColumn("G", typeof(String));
            DataColumn dc8 = new DataColumn("H", typeof(String));
            DataColumn dc9 = new DataColumn("I", typeof(String));
            DataColumn dc10 = new DataColumn("J", typeof(String));
            DataColumn dc11 = new DataColumn("K", typeof(String));
            DataColumn dc12 = new DataColumn("L", typeof(String));
            DataColumn dc13 = new DataColumn("M", typeof(String));
            DataColumn dc14 = new DataColumn("N", typeof(String));
            DataColumn dc15 = new DataColumn("O", typeof(String));
            DataColumn dc16 = new DataColumn("P", typeof(String));
            DataColumn dc17 = new DataColumn("Q", typeof(String));
            DataColumn dc18 = new DataColumn("R", typeof(String));
            DataColumn dc19 = new DataColumn("S", typeof(String));
            DataColumn dc20 = new DataColumn("T", typeof(String));
            DataColumn dc21 = new DataColumn("U", typeof(String));
            DataColumn dc22 = new DataColumn("V", typeof(String));
            DataColumn dc23 = new DataColumn("W", typeof(String));
            DataColumn dc24 = new DataColumn("X", typeof(String));
            DataColumn dc25 = new DataColumn("Y", typeof(String));
            DataColumn dc26 = new DataColumn("Z", typeof(String));
            DataColumn dc27 = new DataColumn("AA", typeof(String));
            DataColumn dc28 = new DataColumn("AB", typeof(String));
            DataColumn dc29 = new DataColumn("AC", typeof(String));
            DataColumn dc30 = new DataColumn("AD", typeof(String));
            DataColumn dc31 = new DataColumn("AE", typeof(String));
            DataColumn dc32 = new DataColumn("AF", typeof(String));
            DataColumn dc33 = new DataColumn("AG", typeof(String));
            DataColumn dc34 = new DataColumn("AH", typeof(String));
            DataColumn dc35 = new DataColumn("AI", typeof(String));
            DataColumn dc36 = new DataColumn("AJ", typeof(String));
            DataColumn dc37 = new DataColumn("AK", typeof(String));
            DataColumn dc38 = new DataColumn("AL", typeof(String));
            DataColumn dc39 = new DataColumn("AM", typeof(String));
            DataColumn dc40 = new DataColumn("AN", typeof(String));
            DataColumn dc41 = new DataColumn("AO", typeof(String));
            DataColumn dc42 = new DataColumn("AP", typeof(String));
            DataColumn dc43 = new DataColumn("AQ", typeof(String));
            DataColumn dc44 = new DataColumn("AR", typeof(String));
            DataColumn dc45 = new DataColumn("AS", typeof(String));

            dt.Columns.Add(dc1);
            dt.Columns.Add(dc2);
            dt.Columns.Add(dc3);
            dt.Columns.Add(dc4);
            dt.Columns.Add(dc5);
            dt.Columns.Add(dc6);
            dt.Columns.Add(dc7);
            dt.Columns.Add(dc8);
            dt.Columns.Add(dc9);
            dt.Columns.Add(dc10);
            dt.Columns.Add(dc11);
            dt.Columns.Add(dc12);
            dt.Columns.Add(dc13);
            dt.Columns.Add(dc14);
            dt.Columns.Add(dc15);
            dt.Columns.Add(dc16);
            dt.Columns.Add(dc17);
            dt.Columns.Add(dc18);
            dt.Columns.Add(dc19);
            dt.Columns.Add(dc20);
            dt.Columns.Add(dc21);
            dt.Columns.Add(dc22);
            dt.Columns.Add(dc23);
            dt.Columns.Add(dc24);
            dt.Columns.Add(dc25);
            dt.Columns.Add(dc26);
            dt.Columns.Add(dc27);
            dt.Columns.Add(dc28);
            dt.Columns.Add(dc29);
            dt.Columns.Add(dc30);
            dt.Columns.Add(dc31);
            dt.Columns.Add(dc32);
            dt.Columns.Add(dc33);
            dt.Columns.Add(dc34);
            dt.Columns.Add(dc35);
            dt.Columns.Add(dc36);
            dt.Columns.Add(dc37);
            dt.Columns.Add(dc38);
            dt.Columns.Add(dc39);
            dt.Columns.Add(dc40);
            dt.Columns.Add(dc41);
            dt.Columns.Add(dc42);
            dt.Columns.Add(dc43);
            dt.Columns.Add(dc44);
            dt.Columns.Add(dc45);

            for (int i = 0; i < 100000; i++)
            {
                DataRow dr = dt.NewRow();
                dr[0] = "Sample text to test";
                dr[1] = "Sample text to test";
                dr[2] = "Sample text to test";
                dr[3] = "Sample text to test";
                dr[4] = "Sample text to test";
                dr[5] = "Sample text to test";
                dr[6] = "Sample text to test";
                dr[7] = "Sample text to test";
                dr[8] = "Sample text to test";
                dr[9] = "Sample text to test";
                dr[10] = 100000*i + 10;
                dr[11] = 100000*i + 11;
                dr[12] = 100000*i + 12;
                dr[13] = 100000*i + 13;
                dr[14] = 100000*i + 14;
                dr[15] = 100000*i + 15;
                dr[16] = 100000*i + 16;
                dr[17] = 100000*i + 17;
                dr[18] = 100000*i + 18;
                dr[19] = 100000*i + 19;
                dr[20] = 100000 * i + 20;
                dr[21] = true;
                dr[22] = true;
                dr[23] = true;
                dr[24] = true;
                dr[25] = true;
                dr[26] = false;
                dr[27] = false;
                dr[28] = false;
                dr[29] = false;
                dr[30] = false;
                dr[31] = XLError.DivisionByZero;
                dr[32] = XLError.NoValueAvailable;
                dr[33] = XLError.IncompatibleValue;
                dr[34] = DateTime.FromOADate(i);
                dr[35] = DateTime.FromOADate(i);
                dr[36] = DateTime.FromOADate(i);
                dr[37] = TimeSpan.FromSeconds(i);
                dr[38] = TimeSpan.FromSeconds(i);
                dr[39] = $"Sample text to test{i}a";
                dr[40] = $"Sample text to test{i}b";
                dr[42] = $"Sample text to test{i}c";
                dr[41] = $"Sample text to test{i}d";
                dr[43] = $"Sample text to test{i}e";
                dr[44] = $"Sample text to test{i}f";

                dt.Rows.Add(dr);
            }

            XLWorkbook wb = new XLWorkbook();
            var ws = wb.Worksheets.Add(dt, "Sheet1");
            ws.Table(0).ShowAutoFilter = false;
            ws.Table(0).Theme = XLTableTheme.None;
            Console.WriteLine("Start saving");
            var sw = Stopwatch.StartNew();
            wb.SaveAs(@"C:\temp\large.xlsx", false);
            sw.Stop();
            Console.WriteLine("Finished saving {0}", sw.Elapsed);
        }
    }
}