Question

I’m making a video game where performance is critical.

I’m using the .Distinct() extension method to get unique value from a List.
Is there a faster way to do so? (even if it means having many more lines of code)

Answer 1

.Distinct is an O(n) call.
You can’t get any faster than that.

However, you should make sure that your GetHashCode (and, to a lesser extent, Equals) is as fast as possible.

Depending on your scenario, you may be able to replace the List<T> with a HashSet<T>, which will prevent duplicates from being inserted in the first place. (yet has O(1) insertion)

However, Always profile your code before jumping to conclusions about what needs to be faster.