Performance Costs of Async/Await in .NET: What Senior Developers Need to Know

As senior .NET developers, we’ve all used async/await as the go-to pattern for handling asynchronous operations. It’s Clean, Intuitive, and makes our code more Maintainable. However, beneath this great syntax lies a complex machinery that can drastically impact application performance when misused.

this article going to uncover the hidden costs and explore optimization strategies that every seasoned developer should know.

Table of Contents

1. Understanding the Foundations
2. Making Your Code Faster: ValueTask
3. Performance Tips ✓
4. Practical Advice for Different Situations
5. Conclusion

BEFORE WE GO :

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Understanding the Foundations

The async/await pattern in .NET fundamentally transforms how we write asynchronous code. Before we learn about advanced patterns, let’s understand what happens under the hood when we write async code.

Async State Machine Flow…

What Actually Happens Behind the Scenes?

When you mark a method as async, .NET does something interesting. It takes your code and transforms it into a special structure called a "state machine."

Think of it like breaking your code into smaller pieces that can be paused and resumed.

Yes, What you write is

public async Task<int> ProcessOrderAsync()
{
    var data = await GetDataAsync();       // Step 1
    var result = await ProcessDataAsync(data); // Step 2
    return result;
}

But, What it becomes (simplified)

public Task<int> ProcessOrderAsync()
{
    // Creates a structure to keep track of where we are
    var stateMachine = new…