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My current technology stack: .NET 9, Python, TypeScript, and Azure.
I develop microservices and terraform of different sizes. Sharing my challenges and key learning.
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The views expressed in this blog are my own and do not reflect my employer's. I am not responsible for any consequences of using the information provided. This blog is for educational purposes only, not for commercial use. Readers should apply their own judgment.
Just-In-Time (JIT) vs. Ahead-of-Time (AOT) Compilation in .NET 9
JIT vs. AOT Compilation in .NET 9
.NET applications can be compiled using Just-In-Time (JIT) compilation or Ahead-Of-Time (AOT) compilation. Each approach has its own strengths and trade-offs.
JIT Compilation in .NET
🔹 Just-In-Time (JIT) compilation compiles Intermediate Language (IL) to native code at runtime.
🔹 Optimizes for the executing CPU, but introduces initial startup overhead.
AOT Compilation in .NET
✅ Starting from .NET 7, Native AOT compiles applications directly to native machine code before execution.
✅ Eliminates JIT overhead, leading to faster startup times and smaller memory footprints.
Performance Comparison
| 🔥 Feature | ⚙️ JIT (Default) | ⚡ AOT (Native) |
|---|---|---|
| 🚀 Startup Time | Slow (JIT Overhead) | Fast (No JIT) |
| ⚡ Execution Speed | Optimized at runtime | Static optimizations |
| 📉 Memory Usage | Higher (JIT metadata) | Lower (No JIT data) |
| 🌎 Portability | CPU-Specific | Precompiled per architecture |
When to Use AOT?
✔ Microservices & Cloud-Native Apps – Fast startup is crucial.
✔ Lightweight CLI Tools – No JIT dependencies.
✔ Constrained Devices – Lower memory consumption.
💡 Conclusion:
JIT is great for dynamic optimizations, while AOT is perfect for fast startup and low memory usage. Choose based on your performance needs!