Let's face it, application performance can virtually make or break the user experience in today's digital world. If your app is slow, users leave, conversions drop, and your brand image suffers. Enter .NET 6 and Blazor, the duo that's transforming how developers build fast, scalable, and high-performance web applications.

.NET 6, Microsoft's latest long-term support (LTS) release, is packed with features that enhance performance, improve developer productivity, and make it easier to build modern web apps. Paired with Blazor, a framework that allows developers to build interactive web applications using C# and .NET, it opens the door to blazing fast, client-side experiences. Let's dive into how you can boost the performance of your web applications using .NET 6 and Blazor.

Understanding Blazor and Its Performance Boosts in .NET 6

Blazor is part of the ASP.NET Core framework and enables developers to write rich web UIs using C# instead of JavaScript. Blazor comes in two flavors: Blazor Server and Blazor WebAssembly (WASM).

• Blazor Server: Runs on the server, sending UI updates to the browser over a SignalR connection.
• Blazor WebAssembly: Runs directly in the browser on WebAssembly, allowing full client-side interactivity without the need for JavaScript.

With .NET 6, both Blazor versions have received significant performance enhancements, making it a perfect choice for building fast, responsive web apps.

1. Enhanced Ahead-of-Time (AOT) Compilation for Blazor WASM

One of the biggest upgrades in .NET 6 for Blazor WebAssembly is the introduction of Ahead-of-Time (AOT) Compilation. In .NET 5, Blazor WebAssembly relied solely on Just-In-Time (JIT) compilation, which meant the app's code was compiled on the client side after being downloaded. This approach could slow down initial load times.

In .NET 6, AOT compilation allows you to compile your Blazor app directly to WebAssembly before it's even shipped to the client. This means the browser no longer needs to compile the app, drastically improving load times and runtime performance.

To enable AOT compilation, you simply need to modify your project file:

<PropertyGroup>
  <BlazorWebAssemblyEnableCompression>true</BlazorWebAssemblyEnableCompression>
  <RunAOTCompilation>true</RunAOTCompilation>
</PropertyGroup>

By using AOT, your Blazor WebAssembly app will feel snappier, with quicker interactions and faster load times, especially for users on slower devices or networks.

2. Reducing Payload Sizes with Lazy Loading

Large applications can suffer from bloated payloads—long initial load times as the entire app is downloaded upfront. But with .NET 6, lazy loading of assemblies has been introduced to address this issue. Lazy loading allows parts of your Blazor WebAssembly app to be loaded only when they are needed, reducing the upfront payload size and improving the app's perceived performance.

Here's a quick example of how you can implement lazy loading for specific assemblies in your Blazor WebAssembly app:

@if (assemblyIsLoaded)
{
    <YourComponent />
}
else
{
    <button @onclick="LoadAssembly">Load Feature</button>
}

@code {
    private bool assemblyIsLoaded = false;

    private async Task LoadAssembly()
    {
        await LazyLoader.LoadAssembliesAsync(new[] { "YourAssembly.dll" });
        assemblyIsLoaded = true;
    }
}

By only loading what the user needs when they need it, you keep the initial download light and fast, improving the overall user experience.

3. Prerendering with Blazor WASM for Instant Feedback

Prerendering is another feature in .NET 6 that can give your Blazor apps a performance edge. With prerendering, the first load of your Blazor WebAssembly app can be processed on the server, providing immediate content to the user while the Blazor WebAssembly app is downloading in the background.

This eliminates the delay where users would normally see a blank page while the WebAssembly payload is being fetched. You can implement prerendering in Blazor using a combination of Blazor WebAssembly and Blazor Server:

1. Configure your Program.cs:
   

   builder.Services.AddRazorComponents();
   builder.RootComponents.Add<App>("#app", RenderMode.ServerPrerendered);
   

2. Ensure your component layout can switch from server prerendering to client-side WebAssembly mode.

This technique provides a nearly instant response to users while the full app continues to load, creating a more seamless user experience.

4. Leveraging .NET 6 Hot Reload for Faster Development

Although not directly tied to production performance, the Hot Reload feature in .NET 6 allows developers to make code changes while the app is running without having to restart the app. This speeds up development cycles and allows you to iterate faster, ensuring your performance optimizations can be tested and implemented more efficiently.

You can enable Hot Reload by simply running your Blazor project with:

dotnet watch run

As you make changes, Hot Reload automatically applies those changes without restarting the entire app, reducing downtime during development.

5. SignalR Performance Enhancements in Blazor Server

For Blazor Server applications, SignalR plays a crucial role in maintaining the connection between the client and the server. In .NET 6, SignalR has been optimized to improve connection stability and message dispatch performance, reducing latency and ensuring faster communication between the server and the client.

Additionally, SignalR in .NET 6 supports Azure SignalR Service, which allows for scaling out SignalR connections in the cloud, further boosting performance in large-scale applications.

6. Optimized JavaScript Interoperability (JS Interop)

While Blazor lets you write C# for almost everything, you might still need to call JavaScript occasionally for specialized functionality. In .NET 6, JS Interop has been optimized for faster communication between C# and JavaScript. This improvement reduces the overhead involved in making JS calls, which can sometimes slow down your application, particularly when making frequent or heavy JS Interop calls.

For example:

[Inject] IJSRuntime JsRuntime { get; set; }

protected async Task TriggerJavaScriptAlert()
{
    await JsRuntime.InvokeVoidAsync("alert", "Hello from Blazor!");
}

The optimized JS Interop in .NET 6 ensures that these calls are handled more efficiently, minimizing performance bottlenecks.

7. Blazor WebAssembly and Web Workers

If your Blazor WebAssembly app needs to perform resource-heavy operations (such as image processing or data analysis), consider using Web Workers. Web Workers allow you to offload computationally expensive tasks to a separate background thread, freeing up the main UI thread and keeping the application responsive.

In .NET 6, you can integrate Web Workers by leveraging JavaScript Web APIs and Blazor's JS Interop. This can greatly improve your app's performance, especially for CPU-bound tasks.

Conclusion

.NET 6 and Blazor have come a long way in delivering high-performance web applications. Whether you're using Blazor WebAssembly for full client-side experiences or Blazor Server for real-time, server-side rendering, the enhancements in .NET 6—from AOT compilation to lazy loading—empower developers to build fast, modern, and scalable web apps.

By combining these techniques, you can dramatically improve the performance of your Blazor apps, offering users a seamless and snappy experience. Remember, in the web world, speed matters—a lot. Take advantage of these features to keep your users engaged, happy, and coming back for more!