π Introduction
In the fast-moving world of web development, performance and observability are the two most important pillars for building reliable and scalable applications.
With ASP.NET Core 9 (2025) and the latest .NET Core runtime, Microsoft has made huge improvements to help developers build faster, smarter, and more observable web applications.
In this article, weβll explore whatβs new, how performance has improved, and how observability tools are evolving for .NET developers.
βοΈ What Do βPerformanceβ and βObservabilityβ Mean?
Before we go deeper, letβs understand these two concepts:
Performance means how efficiently your app handles requests, memory, and CPU β ensuring fast responses and scalability.
Observability means how easily you can understand whatβs happening inside your app through logs, metrics, traces, and profiling.
These two go hand-in-hand. High performance without observability makes debugging difficult, while observability without optimization wastes resources.
π‘ Key Performance Improvements in ASP.NET Core 2025
1. Smarter Just-In-Time (JIT) Compilation
The latest .NET JIT compiler (RyuJIT) has been optimized for:
Faster startup using Dynamic PGO (Profile-Guided Optimization)
Better CPU instruction usage
Reduced memory footprint for long-running APIs
2. Ahead-of-Time (AOT) Compilation for ASP.NET Core
AOT, which was initially for Blazor and console apps, now works for ASP.NET Core web apps.
This creates native executables with:
Example:
If you deploy your ASP.NET Core API to Azure Container Apps or AWS Lambda, AOT drastically improves response speed.
3. Smaller & Faster Kestrel
Kestrel, the built-in web server for ASP.NET Core, has been fine-tuned with:
Zero-copy parsing for HTTP/3
Lower latency TLS handshake
Reduced allocations per request
These changes result in 10β20% better throughput compared to .NET 8.
π§ Flowchart: Performance Workflow in ASP.NET Core 9
Request β Kestrel Web Server β Middleware Pipeline β Controller/Endpoint
β β β
Optimized IO Minimal Allocations Cached Results
β β β
β Faster Response to Client β
This flow shows how ASP.NET Core now handles requests more efficiently from entry to exit.
π§ Observability in .NET 9 / ASP.NET Core 2025
Observability is a top focus for Microsoft in .NET 9.
Now developers can easily monitor performance, diagnose issues, and trace requests across distributed systems.
1. Built-in OpenTelemetry Support
ASP.NET Core 9 now includes native support for OpenTelemetry.
You can export traces, metrics, and logs to any monitoring platform, such as:
Azure Monitor
Grafana
Prometheus
New Relic
Example Configuration
builder.Services.AddOpenTelemetry()
.WithMetrics()
.WithTracing()
.UseOtlpExporter();
This single setup gives you complete observability across your app.
2. Improved Logging System
Structured logging using LoggerMessageAttribute for better performance
Centralized log management with Serilog or Elastic Stack
Built-in JSON logging for cloud environments
Example
[LoggerMessage(EventId = 101, Level = LogLevel.Information, Message = "Request handled for {Endpoint}")]
static partial void LogRequest(ILogger logger, string Endpoint);
This avoids string formatting at runtime, making logs faster and safer.
3. Metrics Collection Made Easy
Using System.Diagnostics.Metrics, you can now track:
API response times
Database latency
Memory usage per request
User sessions
Example
var meter = new Meter("MyAppMetrics");
var counter = meter.CreateCounter<int>("api_request_count");
counter.Add(1, KeyValuePair.Create<string, object?>("endpoint", "/api/products"));
Metrics can be visualized in tools like Grafana or Azure Monitor.
4. Distributed Tracing
Distributed tracing is now natively supported using OpenTelemetry and Activity APIs.
When a user request passes through multiple microservices, each trace is automatically connected β helping you identify where latency occurs.
Client β API Gateway β Order Service β Payment Service β DB
β β β
Trace ID β Span β Span β Span
π₯οΈ Visual Overview (UI Diagram)
+-------------------------------------------------------+
| ASP.NET Core 9 Application |
|-------------------------------------------------------|
| Controllers | Minimal APIs | Razor Pages |
|-------------------------------------------------------|
| Middleware | Caching | Authentication | Rate Limit |
|-------------------------------------------------------|
| Observability Layer |
| β Logging (Serilog, JSON) |
| β Metrics (Prometheus, Grafana) |
| β Tracing (OpenTelemetry) |
+-------------------------------------------------------+
| Performance Enhancements (JIT, AOT, IO) |
+-------------------------------------------------------+
β‘ Practical Tips for Developers
| Area | Tip |
|---|
| Startup Time | Use AOT or ReadyToRun for faster cold starts |
| Memory Optimization | Avoid large in-memory collections; use streaming APIs |
| Caching | Use IMemoryCache or Redis for repeated queries |
| Database Calls | Use async EF Core methods and AsNoTracking() for reads |
| Observability | Configure OpenTelemetry early in pipeline |
π Flowchart: Observability Lifecycle
Event Occurs β Logs Generated β Metrics Recorded β Trace Created
β β β
Data Exported to β OpenTelemetry Collector β Visualization Tools
This helps teams see and understand every part of the app in real time.
𧩠Integration with Cloud & DevOps
ASP.NET Core 9 integrates deeply with:
You can monitor CPU, memory, request times, and errors directly through dashboards.
π Conclusion
With ASP.NET Core 9 and the latest .NET runtime, developers can now build applications that are:
Performance and observability are no longer afterthoughts β they are built-in features.
If youβre maintaining large-scale APIs or enterprise systems, upgrading to ASP.NET Core 9 in 2025 will give you deep visibility, stronger reliability, and unmatched speed.
Other useful article: Serverless Architecture with Angular and ASP.NET Core