Searching ASP.NET Core In-memory list

Question

Having a list stored in-memory in an ASP.NET Core Web API application. Now I want to search for a specific item in the list. If I understand the documentation correctly I've to do it the following way:

List<string> lst = cache.Get("myList");
if (lst.Contains("dog"))  ....;

Assume there are hundreds of concurrent requests, so that the list has to be copied internally hundreds of times concurrently. Is it possible to get only a pointer to the in-memory list and do the search inside this list? Or is there another RAM-saving approach?