Steven Giesel • 8/25/2025

Quick one: Difference between collection expressions and collection initializer

This technical article analyzes the performance difference between C# collection expressions (e.g., `List<int> a = [1, 2, 3];`) and collection initializers (e.g., `List<int> b = new() {1,2,3};`). It shows the lowered code to demonstrate that collection expressions preallocate the list with the exact capacity, offering a potential performance benefit over initializers, which call the Add method for each element.

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#performance #compiler #c