Don't worry. Not everyone knows it...

If you have worked with IEnumerable and using ReSharper , then you may land up into this warning, " Possible Multiple Enumeration of IEnumerable ". So, what this warning is all about? Well, before proceeding further, let’s see how we can store something into IEnumerable object . IEnumerable items = GetAllItems() So, above code itself speaks that items is a variable of type IEnumerable which will hold some values/objects we can iterate through. Now here lies the performance hit, which is also indicated in the form of ReSharper warning. This performance hit may not be significant for a small number of items. But this can be noticed while dealing with a huge number of items. Reason behind this is, whenever you are iterating through items collection, GetAllItems method will be called for the same number of times. Solution : It is always good to materialized the result in a list or array like below: IEnumerable items = GetAllItems().ToList() Once you are done w