For vs. Foreach performance when iterating a generic list

The simplest way is "Test it"!

Performance test:

Code Snippet

9. class Program
10.     {
11.         static void Main(string[] args)
12.         {
13.             
14.             List<int>  list= new List<int>();
15.             for(int i =0; i < 10000000 ; i++)
16.             {
17.                 list.Add(i);
18.             }
19.  
20.             int sum = 0;
21.             Stopwatch sw = new Stopwatch();
22.             sw.Start();
23.             for (int i = 0; i < list.Count; i++)
24.             {
25.                 sum += list[i];
26.             }
27.  
28.             sw.Stop();
29.             Console.WriteLine(" FOR {0}", sw.Elapsed.ToString());
30.             sw.Reset();
31.  
32.             sum = 0;
33.             sw.Start();            
34.             foreach (int item in list)
35.             {
36.                 sum += item;
37.             }
38.             sw.Stop();
39.             Console.WriteLine(" FOREACH {0}", sw.Elapsed.ToString());
40.             sw.Reset();
41.  
42.             Console.ReadLine();
43.         }
44.     }

10 items:
FOR 00:00:00.0000040
FOREACH 00:00:00.0000018

1000 items:
 FOR 00:00:00.0000131
 FOREACH 00:00:00.0000098

100 000 items:
FOR 00:00:00.0010038
FOREACH 00:00:00.0007952

10 000 000 items:
FOR 00:00:00.1031941
FOREACH 00:00:00.0819216

Conclusion:
When you don't need to manipulate items in collection, use Foreach, otherwise For.