Each time we create a new object in .NET, it allocates memory for the object from what is called the managed heap. Eventually, a process called garbage collection kicks in, which is responsible for freeing memory. When the garbage collector performs a collection, it checks for objects in the managed heap that are no longer being used by the app and performs the necessary operations to reclaim their memory.

Memory allocation is very cheap but unfortunately, collecting the memory isn't. Allocating objects over 85 KB in size in a single allocation will result in the object ending up on the large object heap, which is expensive to collect.

So, creating large objects in our .NET code can hurt performance and an area where we can fall into this trap in REST APIs is when dealing with large requests. In this section, we are going to look at the post question endpoint as an example that doesn't have a garbage collection issue with our current implementation. We are going to revise the implementation, introduce a garbage collection issue, and observe the problem using the PerfView tool.