There are many ways to write a loop when using C#. But when iterating you need to be very much aware of the data you are iterating. If you are not being taking good enough care of your code you may suffer from bad performance.

For example when using a property like this property

public static List<string> Strings
{
    get
    {
        Console.WriteLine("GET");
        return new List<string> { "1", "2" };
    }
}

Then you will get completely different results when using one of the following three methods to iterate the items

for (int i = 0; i < Strings.Count; i++)
{
    Console.WriteLine(Strings[i]);
}

For this example the list will be retrieved twice for each iteration of the items. The first problem here is the usage in i < Strings.Count, which for each iteration will retrieve the list and count the items. Then furthermore in Strings[i] the list will be retrieved once again.

var l = Strings.Count;
for (int i = 0; i < l; i++)
{
    Console.WriteLine(Strings[i]);
}

This is a slightly better solution, where the length of the list is stored locally and thus preventing the recount for each iteration. Still foreach Strings[i] the list is retrieved, so the implementation is still a bad solution.

var temp = Strings;
for (int i = 0; i < temp.Count; i++)
{
    Console.WriteLine(temp[i]);
}

This is again a better solution, where the entire list is stored locally and thus the list is retrieved only once and then the local copy is used for each iteration. When doing this you no longer need to worry about the implementation and performance of the get method, as it is only used once.

foreach (string s in Strings)
{
    Console.WriteLine(s);
}

Another solution if you need to iterate all the items, then you can just follow this example which simplifies the code and prevents you from having to store the list locally. The effect is the same as the previous example just without the boilerplate code.

So this should just serve as an example to watch you when using get methods that you do not control.