Collection Performance: Adding Items To a Dictionary

When incorporating items into a Dictionary, the prevalent approach in the code I review involves using the Add() method, as illustrated below:

var collection = new Dictionary<string, Person<Address>>(people.Count);

foreach (var person in personCollection)
{
    collection.Add(person.Key, person.Value);
}

An alternative approach is to utilize the TryAdd() method, which returns a Boolean, as demonstrated below:

var collection = new Dictionary<string,
                     Person<Address>>(people.Count);

foreach (var person in personCollection)
{
    _ = collection.TryAdd(person.Key, person.Value);
}

Benchmark Results

In the benchmark tests, it is evident that the overall performance of TryAdd() is only 1.003 times faster and allocates the same amount of bytes in memory as Add(). My analysis indicates that the performance degrades as more items are added to the collection. For instance, with a count of 16, TryAdd() is 1.073 times more performant. However, at the count of 2,048, the performance shows that using Add() is 1.003 times more performant.

When I setup my EditorConfig to check for these issues, it looks like this: dotnet_diagnostic.CA1864.severity = suggestion

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