C# really needs a GetOrAdd method on the regular Dictionary class (as exists on ConcurrentDictionary). This common pattern (from the optimized version) requires

C# really needs a GetOrAdd method on the regular Dictionary class (as exists on ConcurrentDictionary). This common pattern (from the optimized version) requires the hash function on "word" to be evaluated twice (once for TryGetValue and once for Add). Then, if there is a collision on the 32 bit hash then the equality check needs to be run twice as well. Not good as all of these are O(N) operations (where N is the size of "word"). I suspect the optimized version would be materially faster if they implemented their own dictionary that includes this. if (!counts.TryGetValue(word, out var wordCountRef)) { counts.Add(word, new Ref<int>(1)); }