performance consideration when using properties multiple times

Question

I am using CultureInfo.CurrentCulture when formating my strings using string.format

To quote this blog

This just has the implication that if you are using CurrentCulture a lot, it might be worth reading it into a private variable rather than making lots of calls to CultureInfo.CurrentCulture, otherwise you're using up clock cycles needlessly.

so as per this author

var culture = CultureInfo.CurrentCulture
string.Format(culture,"{0} some format string","some args");
string.Format(culture,"{0} some format string","some other args");

is better than

string.Format(CultureInfo.CurrentCulture,"{0} some format string","some args");
string.Format(CultureInfo.CurrentCulture,"{0} some format string","some other args");

as per MSDN, CultureInfo.CurrentCulture is a property

Is there a performance penalty associated when accessing a property multiple times ??

Also I did some emperical analysis and my tests show me that using a local variable is more expensive than using the property directly.

Stopwatch watch = new Stopwatch();

            int count = 100000000;
            watch.Start();
            for(int i=0;i<count;i++)
            {
                string.Format(CultureInfo.CurrentCulture, "{0} is my name", "ram");
            }


            watch.Stop();
                 //EDIT:Reset watch
                 watch.Reset();


            Console.WriteLine(watch.Elapsed);
            Console.WriteLine(watch.ElapsedMilliseconds);
            Console.WriteLine(watch.ElapsedTicks);


            Console.WriteLine("--------------------");
            var culture = CultureInfo.CurrentCulture;
            watch.Start();
            for (int i=0; i < count; i++)
            {
                string.Format(culture, "{0} is my name", "ram");
            }


            watch.Stop();

            Console.WriteLine(watch.Elapsed);
            Console.WriteLine(watch.ElapsedMilliseconds);
            Console.WriteLine(watch.ElapsedTicks);

Result:

00:00:29.6116306
29611
68922550970
--------------------
00:00:27.3578116
27357
63676674390

My tests show that using CultureInfo.CurrentCulture property is better than using local variable (which contradicts with the authors view). Or am I missing something here ?

Edit:I was not resetting the stopwatch before teh second iteration. hence the difference. resetting stopwatch, updating iteration count and result in this edit

Answer 1

The one true reason to rewrite your code to

var culture = CultureInfo.CurrentCulture;
String.Format(culture, "{0} some format string", "some args"); 
String.Format(culture, "{0} some format string", "some other args"); 

from

String.Format(CultureInfo.CurrentCulture, "{0} some format string", "some args");  
String.Format(CultureInfo.CurrentCulture, "{0} some format string", "some other args"); 

is for readability and maintainability. Now, if you need for some reason to change the culture from CultureInfo.CurrentCulture to a CultureInfo that is loaded via some configuration file or passed in as a method to the parameter you only need to change the code in one place. Performance is a secondary consideration here and probably does not matter in that this is highly unlikely to be a bottleneck in your code.

Answer 2

You should only optimize CultureInfo.CurrentCulture into a local variable if a profiler shows it to be a significant problem in your code and also that putting into a local variable makes it faster. This profile shows neither is true so I would not put it into a local.