How to convert objects with many links to objects without links?

Question

.NET

The garbage collection documentation has an interesting recommendation. If an object contains many references, then the amount of garbage collector work increases. A common trick (especially for large objects) is to convert objects with many references to objects without references (for example, instead of storing a reference, store an index). What is meant? I have never met this before, or maybe I misunderstand what is required.

Answer 1

Use dictionaries to store objects. They hint at it.

Answer 2

Use - Generic Classes (C# Programming Guide)
https://msdn.microsoft.com/en-us/library/sz6zd40f.aspx
For example "List" will store a collection of structs for an int, not boxed objects.
Google for the word "Generic Class".