Click here to Skip to main content
12,549,720 members (48,633 online)
Click here to Skip to main content
Add your own
alternative version

Tagged as


3 bookmarked

Performance comparison of using a List as opposed to an Array

, 17 Jun 2010 CPOL
Rate this:
Please Sign up or sign in to vote.
Benchmark both List and string[].


The objective of this article is to elucidate you, fellow developers, to really evaluate the need of using a generic List<T> instead of an old string[], since usually the cost is overlooked.

Using the Code

I've built a simple example to compare the performance for reading and writing to a List<string> and a string[]. Concerning the writing time in milliseconds, for 100000 randomly generated items, the string[] outperformed the List<string> by approximately 8ms.

const int size = 100000;
Stopwatch startList = new Stopwatch();
List<string> listString = new List<string>(size);
for (int i = 0; i <= size; i++)
    string toAdd = Guid.NewGuid().ToString();
TimeSpan durationList = startList.Elapsed;

Stopwatch startArray = new Stopwatch();
string[] arrayString = new string[size];
for (int i = 0; i < size; i++)
    string toAdd = Guid.NewGuid().ToString();
    arrayString[i] = toAdd;
TimeSpan durationArray= startArray.Elapsed;

When reading, the string[] outperforms the List<string> by approximately 2.5 times faster!!

Stopwatch startListRead = new Stopwatch();
for (int i = 0; i <= listString.Count - 1; i++)
    string str = listString[i];
TimeSpan durationListRead = startListRead.Elapsed;

Stopwatch startArrayRead = new Stopwatch();
for (int i = 0; i <= arrayString.Length - 1; i++)
    string str = arrayString[i];
TimeSpan durationArrayRead = startArrayRead.Elapsed;

And you can still do this with LINQ to Objects with an array, as you do with your List<string>:

//Perform our LINQ query on an Array just like a List<T>
var result = from i in arrayString
         where i.StartsWith("a")
         select i;



So, bottom line, you should consider if you really need the List<T> as opposed to an array because there are serious performance costs that will affect your application.

Points of Interest

Creating concerns on performance of instructions being used in your applications.


This article, along with any associated source code and files, is licensed under The Code Project Open License (CPOL)


About the Author

Software Developer (Senior) Truphone
Portugal Portugal
No Biography provided

You may also be interested in...


Comments and Discussions

Questionlist<>.Count Kills Reading Performance Pin
MountainGhost30-Aug-12 6:41
memberMountainGhost30-Aug-12 6:41 
GeneralMy vote of 5 Pin
Dan Randolph8-Jul-12 6:17
memberDan Randolph8-Jul-12 6:17 
GeneralRe: My vote of 5 Pin
Dan Randolph8-Jul-12 7:00
memberDan Randolph8-Jul-12 7:00 
GeneralMy vote of 1 Pin
krishnabhargav16-Jun-10 13:50
memberkrishnabhargav16-Jun-10 13:50 
GeneralRe: My vote of 1 Pin
ricrodrigues16-Jun-10 23:33
memberricrodrigues16-Jun-10 23:33 
AnswerAbout accuracy Pin
Niklas Lindquist17-Jun-10 2:48
memberNiklas Lindquist17-Jun-10 2:48 
GeneralRe: About accuracy Pin
ricrodrigues17-Jun-10 3:21
memberricrodrigues17-Jun-10 3:21 
GeneralRe: About accuracy Pin
ricrodrigues17-Jun-10 3:33
memberricrodrigues17-Jun-10 3:33 
Generalhad similar results ... BUt Pin
krishnabhargav16-Jun-10 13:29
memberkrishnabhargav16-Jun-10 13:29 
GeneralRe: had similar results ... BUt Pin
ricrodrigues16-Jun-10 23:33
memberricrodrigues16-Jun-10 23:33 

General General    News News    Suggestion Suggestion    Question Question    Bug Bug    Answer Answer    Joke Joke    Praise Praise    Rant Rant    Admin Admin   

Use Ctrl+Left/Right to switch messages, Ctrl+Up/Down to switch threads, Ctrl+Shift+Left/Right to switch pages.

| Advertise | Privacy | Terms of Use | Mobile
Web02 | 2.8.161021.1 | Last Updated 17 Jun 2010
Article Copyright 2010 by ricmrodrigues
Everything else Copyright © CodeProject, 1999-2016
Layout: fixed | fluid