.NET 8 continues Microsoft’s focus on performance, productivity, and modernization. Whether you’re building APIs, microservices, desktop apps, or cloud-native solutions, .NET 8 brings significant improvements and new capabilities to help you deliver better software faster.

In this comprehensive guide, we’ll explore:

• Major updates in .NET 8 compared to previous versions
• New features in ASP.NET Core
• Blazor’s evolution into full-stack web development
• Native AOT compilation improvements
• Middleware enhancements, including rate limiting
• Performance upgrades across the framework
• Real-world use cases and code examples

This guide is intended for experienced .NET developers who want to stay current and leverage .NET 8’s full potential.

🔍 Overview: Why .NET 8 Matters

.NET 8 is a Long-Term Support (LTS) release, supported for three years. It builds on .NET 7’s foundation with major enhancements to performance, diagnostics, and cloud-native support.

Highlights:

• LTS status ensures long-term stability
• Native AOT compilation is now production-grade
• Blazor unifies front-end and back-end development
• Minimal APIs gain more flexibility
• New built-in middleware simplifies security and rate limiting

Let’s dig into the most important features.

🚀 Native AOT Improvements

What is Native AOT?

Native AOT (Ahead-Of-Time compilation) produces a standalone, platform-specific binary. It compiles IL directly into native code at publish time—no JIT compilation required at runtime.

What’s New in .NET 8?

• Native AOT now supports ASP.NET Core apps
• Better trimming support with fewer runtime dependencies
• Improved diagnostics for AOT apps
• Support for reflection-heavy libraries via DynamicDependency

Why it Matters

• Instant startup time (sub-millisecond in many cases)
• Smaller binaries
• No need for runtime installation
• Ideal for containerized workloads and microservices

Before vs After

Code Example

# Publish a minimal API as AOT
DOTNET_EnableWriteXorExecute=1 dotnet publish -c Release -r linux-x64 --self-contained true /p:PublishAot=true

⚡ ASP.NET Core Upgrades

ASP.NET Core continues to lead in high-performance web frameworks. In .NET 8, Microsoft focused on both speed and developer experience.

Key Enhancements:

1. Output caching
   • New OutputCacheMiddleware replaces ResponseCache
   • Supports tag helpers and minimal APIs
2. Rate Limiting Middleware
   • Built-in support for IP/endpoint-based request limiting
3. New Middleware APIs
   • IStartupFilter, UseShortCircuit, and more
4. Performance Tweaks
   • Optimized HTTP/2 and HTTP/3 handling
   • Reduced allocations across the board

Code Example: Rate Limiting

builder.Services.AddRateLimiter(options =>
{
    options.AddFixedWindowLimiter("default", o =>
    {
        o.PermitLimit = 5;
        o.Window = TimeSpan.FromSeconds(10);
    });
});

app.UseRateLimiter();

Benchmark:

In Microsoft’s own tests, ASP.NET Core on .NET 8 hit over 2 million RPS (requests per second) in optimized scenarios.

🧱 Blazor Gets Full Stack Power

Blazor in .NET 8 enables hybrid rendering, combining server-side and WebAssembly in the same app. It’s now a full-stack framework.

Key Features:

• Interactive SSR: Blazor Server + streaming + hydration
• Blazor WebAssembly with AOT: Faster client-side rendering
• New Navigation and Layout improvements
• Enhanced form handling and validation

Why it’s Game-Changing

• One framework for both frontend and backend
• Shared code between server and client
• Easier testing and deployment

Code Sample: Toggle rendering modes

@page "/weather"
@using Microsoft.AspNetCore.Components.Web

<WeatherForecast />

🔒 Built-in Middleware: Rate Limiting & Output Caching

.NET 8 introduces first-class middleware for:

• Output caching (by route, header, query)
• Rate limiting (global or per-route)
• Keyed services

Example: Caching

app.MapGet("/time", () => DateTime.UtcNow)
    .CacheOutput(o => o.Expire(TimeSpan.FromSeconds(30)));

This saves you from writing your own cache logic or installing third-party packages.

🔬 Diagnostics & Observability

.NET 8 greatly enhances telemetry and diagnostics:

• Native AOT apps can emit logs
• Better integration with OpenTelemetry
• Improved counters, traces, and metrics

Example: Enabling OpenTelemetry

builder.Services.AddOpenTelemetry().WithTracing(tracing =>
{
    tracing.AddAspNetCoreInstrumentation();
    tracing.AddHttpClientInstrumentation();
});

🧪 Minimal API Improvements

Minimal APIs get more powerful in .NET 8:

• Route groups and named filters
• OpenAPI support with conventions
• Strongly typed Results<T>

Example: Grouped endpoints with filters

var group = app.MapGroup("/admin").RequireAuthorization();

group.MapGet("/users", GetUsers);
group.MapPost("/users", CreateUser);

📈 Performance Gains Across the Stack

.NET 8 is faster than ever:

• JSON serialization improved
• JIT compilation tuned
• Span and Memory optimized
• Better performance in collection classes

Numbers:

• JSON write speeds up to 30% faster
• Memory usage down by 20% for many workloads
• ASP.NET Core throughput increased by 15–40%

✅ Migration Tips

Ready to move from .NET 6/7 to .NET 8? Follow these steps:

1. Update TargetFramework to net8.0
2. Replace deprecated packages (e.g., Microsoft.AspNetCore.*)
3. Test trimming/AOT compatibility if using Native AOT
4. Use dotnet workload update for latest SDK tooling
5. Run performance and memory profiling before/after migration

🧰 Tools and Resources

• Official .NET 8 Release Notes
• .NET Upgrade Assistant
• BenchmarkDotNet
• dotnet-counters

📌 Summary

.NET 8 is a huge leap forward in building fast, modern, and scalable applications:

• Native AOT brings lightning-fast performance and portability
• ASP.NET Core is more powerful and minimal
• Blazor is now full-stack ready
• Built-in middleware makes everyday scenarios easier
• Performance wins are everywhere

If you’re building with .NET in 2025 and beyond, .NET 8 is the version to be on.

Stay tuned for part two: Harnessing Native AOT in .NET 8: Faster, Smaller, Sharper.