.NET Fiddle

CSharp · Console

/Program.cs

using System;
using System.Collections.Generic;
using System.Linq;				
using System.Reflection;
using System.Diagnostics;

public class Person
{
	public string Name { get; set; }
	public int Age { get; set; }
}

public class Program
{
	public static void Main()
	{

        List<Person> personList = new List<Person>();
        personList.Add(new Person(){Name = "aaa", Age = 10});
        personList.Add(new Person(){Name = "bbb", Age = 5});
        for(int i = 0; i< 10; i++)
		{
			personList.AddRange(personList);
		}

		
        Dictionary<string, PropertyInfo> propDict = typeof(Person).GetProperties(BindingFlags.Public | BindingFlags.Instance)
            .Where(p => p.CanRead && !p.GetIndexParameters().Any()).AsEnumerable().ToDictionary(x => x.Name, x => x);
        int count = personList.Count;
		
		Stopwatch sw = new Stopwatch();
		//1. get Object[]
		sw.Restart();
		foreach(var prop in propDict)
        {
			var tempArray = personList.Select(x => prop.Value.GetValue(x)).ToArray();
            Console.WriteLine(tempArray.GetType().Name);//Object[]
        }
		sw.Stop();
		Console.WriteLine("Spend" + sw.ElapsedMilliseconds + "us");
		
		//2. not work, return Object[]
		sw.Restart();
		foreach(var prop in propDict)
        {
			var tempArray = personList.Select(x => Convert.ChangeType(prop.Value.GetValue(x), prop.Value.PropertyType)).ToArray();
            Console.WriteLine(tempArray.GetType().Name);//Object[]
        }
		sw.Stop();
		Console.WriteLine("Spend" + sw.ElapsedMilliseconds + "us");
		
		//3. work, via ArrayCopy, try to find other method
		sw.Restart();
		foreach(var prop in propDict)
        {
			var tempArray = personList.Select(x => prop.Value.GetValue(x)).ToArray();
            Array stronglyTypeArray = Array.CreateInstance(prop.Value.PropertyType, count);
			Array.Copy(tempArray, stronglyTypeArray, count);
			Console.WriteLine(stronglyTypeArray.GetType().Name);//String[]//Int32[]
        }
		sw.Stop();
		Console.WriteLine("Spend" + sw.ElapsedMilliseconds + "us");
		
		//4. work, if-condition slower than method 3
		sw.Restart();
		foreach(var prop in propDict)
        {
			dynamic tempArray;
			if(prop.Value.PropertyType == typeof(System.String))
			{
				tempArray = personList.Select(x =>  prop.Value.GetValue(x).ToString()).ToArray();
			}
			else if(prop.Value.PropertyType == typeof(System.Boolean))
			{
				tempArray = personList.Select(x =>  (bool)prop.Value.GetValue(x)).ToArray();
			}
			else if(prop.Value.PropertyType == typeof(System.Byte))
			{
				tempArray = personList.Select(x =>  (byte)prop.Value.GetValue(x)).ToArray();
			}
			else if(prop.Value.PropertyType == typeof(System.Char))
			{
				tempArray = personList.Select(x =>  (char)prop.Value.GetValue(x)).ToArray();
			}
			else if(prop.Value.PropertyType == typeof(System.Decimal))
			{
				tempArray = personList.Select(x =>  (decimal)prop.Value.GetValue(x)).ToArray();
			}
			else if(prop.Value.PropertyType == typeof(System.Double))
			{
				tempArray = personList.Select(x =>  (double)prop.Value.GetValue(x)).ToArray();
			}
			else if(prop.Value.PropertyType == typeof(System.Int16))
			{
				tempArray = personList.Select(x =>  (short)prop.Value.GetValue(x)).ToArray();
			}
			else if(prop.Value.PropertyType == typeof(System.Int32))
			{
				tempArray = personList.Select(x =>  (int)prop.Value.GetValue(x)).ToArray();
			}
			else if(prop.Value.PropertyType == typeof(System.Int64))
			{
				tempArray = personList.Select(x =>  (long)prop.Value.GetValue(x)).ToArray();
			}
			else if(prop.Value.PropertyType == typeof(System.Single))
			{
				tempArray = personList.Select(x =>  (float)prop.Value.GetValue(x)).ToArray();
			}
			else
			{
				tempArray = personList.Select(x =>  prop.Value.GetValue(x)).ToArray();
			}
			Console.WriteLine(tempArray.GetType().Name);//Object[]
        }
		sw.Stop();
		Console.WriteLine("Spend" + sw.ElapsedMilliseconds + "us");
	}
}