Beyond LINQ: High-Performance Collection Processing in Modern .NET

After years of building high-performance .NET applications, I’ve seen countless developers unknowingly sacrifice performance at the altar of LINQ’s convenience. While LINQ’s declarative syntax is beautiful, it’s time we had an honest conversation about its performance implications and modern alternatives!

The Real Cost of LINQ: Beyond Basic Benchmarks

Let’s start with a controversial statement: Your favorite LINQ methods might be killing your application’s performance.

Reason: look at this [ Seemingly innocent LINQ ]

// Common LINQ pattern many developers use
var result = orders
    .Where(o => o.Status == OrderStatus.Pending)
    .Select(o => new OrderDTO 
    { 
        Id = o.Id, 
        Total = o.Items.Sum(i => i.Price) 
    })
    .OrderByDescending(o => o.Total)
    .Take(10)
    .ToList();

Here’s what’s actually happening under the hood:

1. Multiple iterator allocations (one for each operation)
2. Delegate allocations for each lambda
3. Deferred execution complexity
4. Hidden intermediate collections
5. Boxing/unboxing operations