List.Add vs HashSet.Add for small collections in c#

Question

Given

HashSet<T> set;
List<T> list;
T t;

Which of these performs better for SMALL collections?

if (! list.Contains (t)) list.Add (t);

Or

set.Add (t);

Source of doubt: HashSet vs. List performance

Answer 1

It really has to do with how you are going to use the data structures. If you need to access an item using an index, then you can't use a HashSet, also if you need to store duplicates, you can;t use HashSet. A List is typically used for most operations, so I you don't understand the underlying design and functionality of the HashSet, then chances are a List will suffice.