diff --git a/ClosedXML/ClosedXML/ClosedXML_Sandbox/ClosedXML_Sandbox.csproj b/ClosedXML/ClosedXML/ClosedXML_Sandbox/ClosedXML_Sandbox.csproj
index 4fe60b4..9f6d804 100644
--- a/ClosedXML/ClosedXML/ClosedXML_Sandbox/ClosedXML_Sandbox.csproj
+++ b/ClosedXML/ClosedXML/ClosedXML_Sandbox/ClosedXML_Sandbox.csproj
@@ -1,5 +1,5 @@
 <?xml version="1.0" encoding="utf-8"?>
-<Project ToolsVersion="4.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
+<Project ToolsVersion="12.0" DefaultTargets="Build" xmlns="http://schemas.microsoft.com/developer/msbuild/2003">
   <PropertyGroup>
     <Configuration Condition=" '$(Configuration)' == '' ">Debug</Configuration>
     <Platform Condition=" '$(Platform)' == '' ">x86</Platform>
@@ -10,7 +10,7 @@
     <AppDesignerFolder>Properties</AppDesignerFolder>
     <RootNamespace>ClosedXML_Sandbox</RootNamespace>
     <AssemblyName>ClosedXML_Sandbox</AssemblyName>
-    <TargetFrameworkVersion>v4.0</TargetFrameworkVersion>
+    <TargetFrameworkVersion>v4.5.1</TargetFrameworkVersion>
     <TargetFrameworkProfile>
     </TargetFrameworkProfile>
     <FileAlignment>512</FileAlignment>
@@ -30,6 +30,7 @@
     <DefineConstants>DEBUG;TRACE</DefineConstants>
     <ErrorReport>prompt</ErrorReport>
     <WarningLevel>4</WarningLevel>
+    <Prefer32Bit>false</Prefer32Bit>
   </PropertyGroup>
   <PropertyGroup Condition=" '$(Configuration)|$(Platform)' == 'Release|x86' ">
     <PlatformTarget>AnyCPU</PlatformTarget>
@@ -39,6 +40,7 @@
     <DefineConstants>TRACE</DefineConstants>
     <ErrorReport>prompt</ErrorReport>
     <WarningLevel>4</WarningLevel>
+    <Prefer32Bit>false</Prefer32Bit>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Debug|x64'">
     <DebugSymbols>true</DebugSymbols>
@@ -55,6 +57,7 @@
     <CodeAnalysisIgnoreBuiltInRuleSets>true</CodeAnalysisIgnoreBuiltInRuleSets>
     <CodeAnalysisRuleDirectories>;C:\Program Files (x86)\Microsoft Visual Studio 10.0\Team Tools\Static Analysis Tools\FxCop\\Rules</CodeAnalysisRuleDirectories>
     <CodeAnalysisIgnoreBuiltInRules>true</CodeAnalysisIgnoreBuiltInRules>
+    <Prefer32Bit>false</Prefer32Bit>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Release|x64'">
     <OutputPath>bin\x64\Release\</OutputPath>
@@ -71,6 +74,7 @@
     <CodeAnalysisIgnoreBuiltInRuleSets>true</CodeAnalysisIgnoreBuiltInRuleSets>
     <CodeAnalysisRuleDirectories>;C:\Program Files (x86)\Microsoft Visual Studio 10.0\Team Tools\Static Analysis Tools\FxCop\\Rules</CodeAnalysisRuleDirectories>
     <CodeAnalysisIgnoreBuiltInRules>true</CodeAnalysisIgnoreBuiltInRules>
+    <Prefer32Bit>false</Prefer32Bit>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Debug|AnyCPU'">
     <DebugSymbols>true</DebugSymbols>
@@ -87,6 +91,7 @@
     <CodeAnalysisIgnoreBuiltInRuleSets>true</CodeAnalysisIgnoreBuiltInRuleSets>
     <CodeAnalysisRuleDirectories>;C:\Program Files (x86)\Microsoft Visual Studio 10.0\Team Tools\Static Analysis Tools\FxCop\\Rules</CodeAnalysisRuleDirectories>
     <CodeAnalysisIgnoreBuiltInRules>false</CodeAnalysisIgnoreBuiltInRules>
+    <Prefer32Bit>false</Prefer32Bit>
   </PropertyGroup>
   <PropertyGroup Condition="'$(Configuration)|$(Platform)' == 'Release|AnyCPU'">
     <OutputPath>bin\Release\</OutputPath>
@@ -103,12 +108,14 @@
     <CodeAnalysisIgnoreBuiltInRuleSets>true</CodeAnalysisIgnoreBuiltInRuleSets>
     <CodeAnalysisRuleDirectories>;C:\Program Files (x86)\Microsoft Visual Studio 10.0\Team Tools\Static Analysis Tools\FxCop\\Rules</CodeAnalysisRuleDirectories>
     <CodeAnalysisIgnoreBuiltInRules>true</CodeAnalysisIgnoreBuiltInRules>
+    <Prefer32Bit>false</Prefer32Bit>
   </PropertyGroup>
   <ItemGroup>
     <Reference Include="DocumentFormat.OpenXml, Version=2.5.5631.0, Culture=neutral, PublicKeyToken=31bf3856ad364e35, processorArchitecture=MSIL">
       <Private>True</Private>
     </Reference>
     <Reference Include="System" />
+    <Reference Include="System.ComponentModel.DataAnnotations" />
     <Reference Include="System.Core" />
     <Reference Include="System.Drawing" />
     <Reference Include="System.Xml.Linq" />
@@ -119,8 +126,10 @@
     <Reference Include="WindowsBase" />
   </ItemGroup>
   <ItemGroup>
+    <Compile Include="PerformanceRunner.cs" />
     <Compile Include="Program.cs" />
     <Compile Include="Properties\AssemblyInfo.cs" />
+    <Compile Include="OneRow.cs" />
   </ItemGroup>
   <ItemGroup>
     <None Include="app.config" />
diff --git a/ClosedXML/ClosedXML/ClosedXML_Sandbox/OneRow.cs b/ClosedXML/ClosedXML/ClosedXML_Sandbox/OneRow.cs
new file mode 100644
index 0000000..0dde282
--- /dev/null
+++ b/ClosedXML/ClosedXML/ClosedXML_Sandbox/OneRow.cs
@@ -0,0 +1,89 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Web;
+using System.ComponentModel.DataAnnotations;
+
+namespace ClosedXML_Sandbox
+{
+    public class OneRow
+    {
+        [Display(Name = "Col01")]
+        public int Col01 { get; set; }
+
+        [Display(Name = "Col02")]
+        public string Col02 { get; set; }
+
+        [Display(Name = "Col03")]
+        public DateTime? Col03 { get; set; }
+
+        [Display(Name = "Col04")]
+        public TimeSpan? Col04 { get; set; }
+
+        [Display(Name = "Col05")]
+        public TimeSpan? Col05 { get; set; }
+
+        [Display(Name = "Col06")]
+        public TimeSpan? Col06 { get; set; }
+
+        [Display(Name = "Col07")]
+        public TimeSpan? Col07 { get; set; }
+
+        [Display(Name = "Col08")]
+        public TimeSpan? Col08 { get; set; }
+
+        [Display(Name = "Col09")]
+        public string Col09 { get; set; }
+
+        [Display(Name = "Col10")]
+        public decimal Col10 { get; set; }
+
+        [Display(Name = "Col11")]
+        public string Col11 { get; set; }
+
+        [Display(Name = "Col12")]
+        public bool Col12 { get; set; }
+
+        [Display(Name = "Col13")]
+        public bool Col13 { get; set; }
+
+        [Display(Name = "Col14")]
+        public string Col14 { get; set; }
+
+        [Display(Name = "Col15")]
+        public bool Col15 { get; set; }
+
+        [Display(Name = "Col16")]
+        public string Col16 { get; set; }
+
+        [Display(Name = "Col17")]
+        public string Col17 { get; set; }
+
+        [Display(Name = "Col18")]
+        public DateTime? Col18 { get; set; }
+
+        [Display(Name = "Col19")]
+        public string Col19 { get; set; }
+
+        [Display(Name = "Col20")]
+        public string Col20 { get; set; }
+
+        [Display(Name = "Col21")]
+        public string Col21 { get; set; }
+
+        [Display(Name = "Col22")]
+        public string Col22 { get; set; }
+
+        [Display(Name = "Col23")]
+        public string Col23 { get; set; }
+
+        [Display(Name = "Col24")]
+        public bool Col24 { get; set; }
+
+        [Display(Name = "Col25")]
+        public int? Col25 { get; set; }
+
+        [Display(Name = "Col26")]
+        public string Col26 { get; set; }
+    }
+}
\ No newline at end of file
diff --git a/ClosedXML/ClosedXML/ClosedXML_Sandbox/PerformanceRunner.cs b/ClosedXML/ClosedXML/ClosedXML_Sandbox/PerformanceRunner.cs
new file mode 100644
index 0000000..97d3a31
--- /dev/null
+++ b/ClosedXML/ClosedXML/ClosedXML_Sandbox/PerformanceRunner.cs
@@ -0,0 +1,128 @@
+using ClosedXML.Excel;
+using System;
+using System.Collections.Generic;
+using System.Diagnostics;
+using System.IO;
+using System.Linq;
+using System.Text;
+
+namespace ClosedXML_Sandbox
+{
+    internal class PerformanceRunner
+    {
+        public static void TimeAction(Action action)
+        {
+            var stopwatch = Stopwatch.StartNew();
+            action();
+            Console.WriteLine("Action done in " + stopwatch.Elapsed);
+        }
+
+        const int rowCount = 5000;
+        public static void RunInsertTable()
+        {
+            var rows = new List<OneRow>();
+
+            for (int i = 0; i < rowCount; i++)
+            {
+                var row = GenerateRow<OneRow>();
+                rows.Add(row);
+            }
+
+            var workbook = new XLWorkbook();
+            var worksheet = workbook.Worksheets.Add("Sheet 1");
+            worksheet.Cell(1, 1).InsertTable(rows);
+
+            CreateMergedCell(worksheet);
+
+            worksheet.Columns().AdjustToContents();
+
+            EmulateSave(workbook);
+        }
+
+        private static void CreateMergedCell(IXLWorksheet worksheet)
+        {
+            worksheet.Cell(rowCount + 2, 1).Value = "Merged cell";
+            var range = worksheet.Range(rowCount + 2, 1, rowCount + 2, 2);
+            range.Row(1).Merge();
+        }
+
+        private static void EmulateSave(XLWorkbook workbook)
+        {
+            using (MemoryStream memoryStream = new MemoryStream())
+            {
+                workbook.SaveAs(memoryStream);
+                memoryStream.Seek(0, SeekOrigin.Begin);
+                Console.WriteLine("Total bytes = " + memoryStream.ToArray().Length);
+            }
+        }
+
+        private static Random rnd = new Random();
+
+        private static T GenerateRow<T>() where T : new()
+        {
+            var row = new T();
+
+            var rowProps = row.GetType().GetProperties();
+
+            var strings = rowProps.Where(p => p.PropertyType == typeof(string));
+            var decimals = rowProps.Where(p => p.PropertyType == typeof(decimal));
+            var ints = rowProps.Where(p => p.PropertyType == typeof(int) || p.PropertyType == typeof(int?));
+            var dates = rowProps.Where(p => p.PropertyType == typeof(DateTime?));
+            var timeSpans = rowProps.Where(p => p.PropertyType == typeof(TimeSpan?));
+            var booleans = rowProps.Where(p => p.PropertyType == typeof(bool));
+
+            // Format strings
+            var tmpString = new StringBuilder();
+            var tmpStringLength = rnd.Next(5, 50);
+            for (int x = 0; x <= tmpStringLength; x++)
+            {
+                tmpString.Append((char)(rnd.Next(48, 120)));
+            }
+            foreach (var str in strings)
+            {
+                str.SetValue(row, tmpString.ToString());
+            }
+
+            // Format decimals
+            var tmpDec = (decimal)(rnd.Next(-10000, 100000) / (Math.Pow(10.0, rnd.Next(1, 4))));
+
+            foreach (var dec in decimals)
+            {
+                dec.SetValue(row, tmpDec);
+            }
+
+            // Format ints
+            var tmpInt = rnd.Next(-1000, 10000);
+
+            foreach (var intValue in ints)
+            {
+                intValue.SetValue(row, tmpInt);
+            }
+
+            // Format dates
+            var tmpDate = new DateTime(2012, 1, 1, 1, 1, 1);
+            tmpDate = tmpDate.AddSeconds(rnd.Next(-10000, 100000));
+            foreach (var dt in dates)
+            {
+                dt.SetValue(row, tmpDate);
+            }
+
+            // Format timespans
+            var tmpTimespan = new TimeSpan(rnd.Next(1, 24), rnd.Next(1, 60), rnd.Next(1, 60));
+
+            foreach (var ts in timeSpans)
+            {
+                ts.SetValue(row, tmpTimespan);
+            }
+
+            // Format booleans
+            var tmpBool = (rnd.Next(0, 2) > 0);
+            foreach (var bl in booleans)
+            {
+                bl.SetValue(row, tmpBool);
+            }
+
+            return row;
+        }
+    }
+}
diff --git a/ClosedXML/ClosedXML/ClosedXML_Sandbox/Program.cs b/ClosedXML/ClosedXML/ClosedXML_Sandbox/Program.cs
index abacd10..f01eb1d 100644
--- a/ClosedXML/ClosedXML/ClosedXML_Sandbox/Program.cs
+++ b/ClosedXML/ClosedXML/ClosedXML_Sandbox/Program.cs
@@ -15,9 +15,13 @@
     {
         private static void Main(string[] args)
         {
-            var wb = new XLWorkbook();
-            wb.SaveAs(@"c:\temp\saved.xlsx");
-            Console.WriteLine("Done");
+            //var wb = new XLWorkbook();
+            //wb.SaveAs(@"c:\temp\saved.xlsx");
+            //Console.WriteLine("Done");
+            PerformanceRunner.TimeAction(PerformanceRunner.RunInsertTable);
+
+            Console.WriteLine("Press any key to continue");
+            Console.ReadKey();
         }
     }
 }
diff --git a/ClosedXML/ClosedXML/ClosedXML_Sandbox/app.config b/ClosedXML/ClosedXML/ClosedXML_Sandbox/app.config
index cb2586b..22c902a 100644
--- a/ClosedXML/ClosedXML/ClosedXML_Sandbox/app.config
+++ b/ClosedXML/ClosedXML/ClosedXML_Sandbox/app.config
@@ -1,3 +1,3 @@
 <?xml version="1.0"?>
 <configuration>
-<startup><supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.0"/></startup></configuration>
+<startup><supportedRuntime version="v4.0" sku=".NETFramework,Version=v4.5.1"/></startup></configuration>