If you’ve been developing with .NET for a while, you already know how much the Garbage Collector (GC) does for us behind the scenes. It’s one of those invisible heroes that silently keeps our applications running smoothly by automatically reclaiming unused memory. Without it, we’d be stuck manually managing allocations and deallocations like in C or C++.
With the release of .NET 10, the Garbage Collector has received major improvements in performance, memory compaction, and efficiency. These changes are not just theoretical—they have real-world impact on the performance and scalability of web apps, APIs, desktop software, and even cloud-native workloads.
In this blog, we’ll take a deep dive into the GC improvements in .NET 10, focusing on memory compaction, reduced fragmentation, faster allocations, and improved scalability. Whether you’re a backend engineer, a full-stack developer, or someone curious about performance tuning, you’ll walk away with practical knowledge on how .NET 10 helps your apps run better with zero extra effort from you.
Why Garbage Collection Matters in .NET
Before we jump into the new features, let’s refresh our understanding.
In .NET, the Garbage Collector is responsible for:
- Automatically freeing unused memory so developers don’t have to manually release objects.
- Reducing memory leaks by ensuring unreachable objects are removed.
- Managing heap generations (Gen 0, Gen 1, Gen 2, Large Object Heap) for efficient allocation.
- Keeping applications performant by compacting memory and reducing fragmentation.
In earlier versions, the GC was already very efficient. But as applications scale to handle cloud traffic, microservices, real-time APIs, and massive datasets, the pressure on memory increases. That’s where .NET 10’s new GC improvements come in.
The Key Garbage Collector Improvements in .NET 10
1. Smarter Memory Compaction
Memory compaction is the process of reorganizing live objects in memory to reduce fragmentation. Think of it like cleaning up your desk—moving the papers into one neat stack instead of leaving them scattered.
In .NET 10:
- Compaction algorithms have been re-optimized to run with lower overhead.
- The GC is now smarter in deciding when and how much to compact, balancing CPU cycles with memory savings.
- Large Object Heap (LOH) compaction has been improved, reducing fragmentation that often led to high memory usage in long-running apps.
Impact for developers:
If your app runs for hours or days (like a web API or a background worker), memory fragmentation can cause unnecessary growth in memory usage. With .NET 10, the runtime automatically reduces this problem, keeping memory usage lower and more stable.
2. Improved Large Object Heap (LOH) Handling
Objects over 85 KB are stored in the Large Object Heap (LOH). In older versions of .NET, LOH compaction was limited and often caused memory bloat in high-load scenarios.
In .NET 10:
- LOH compaction runs more predictably and with less pause time.
- The GC can compact LOH in parallel with other operations, reducing application pauses.
- Fragmentation in LOH is reduced, which is especially helpful for image processing, serialization-heavy workloads, or large data processing apps.
Impact: Apps that handle large arrays, JSON documents, or media files will see lower memory usage and fewer OutOfMemory exceptions.
3. Better Scaling for Cloud & Multi-Core CPUs
As cloud-native apps run on VMs with dozens (or even hundreds) of cores, scaling the GC efficiently is critical.
.NET 10 introduces:
- Improved parallel GC – multiple threads can collect and compact memory at once.
- Better scalability across NUMA (Non-Uniform Memory Access) systems.
- Optimized background GC for smoother performance under heavy load.
Impact: Your ASP.NET Core APIs, Blazor apps, or background jobs running in Kubernetes can scale more efficiently with fewer GC pauses, especially on high-core cloud machines.
4. Reduced GC Pause Times
Nothing frustrates users more than random slowdowns. GC pauses can cause hiccups in responsiveness, especially in UI or real-time applications.
.NET 10 reduces pause times by:
- Making compaction more incremental instead of pausing everything at once.
- Introducing region-based compaction, where only parts of the heap are compacted instead of the whole thing.
- Allowing work-stealing between GC threads for faster completion.
Impact: Apps like games, trading systems, or live dashboards will feel smoother, with fewer noticeable pauses.
5. Lower Memory Footprint Out of the Box
One of the hidden gems of .NET 10’s GC is that it’s just more memory-efficient overall.
- Small object heaps grow more slowly.
- Fragmentation is reduced across all generations.
- Background GC has been optimized to reclaim unused memory more aggressively.
This means your application will likely consume less memory on average, which directly translates to lower cloud hosting costs if you’re running on Azure, AWS, or GCP.
Real-World Example: .NET 9 vs .NET 10
Imagine you’re running an ASP.NET Core Web API that handles 10,000 requests per second. Each request serializes/deserializes JSON, touches large objects, and holds data in memory temporarily.
On .NET 9:
- Memory usage might climb to 3 GB after several hours.
- GC pauses occasionally spike latency to 300ms.
On .NET 10:
- Memory usage stabilizes around 2 GB due to better compaction.
- GC pauses rarely exceed 50ms.
- Average latency improves by ~15%.
You didn’t change a single line of code—the GC just got smarter.
How Developers Can Take Advantage
The best part? You don’t have to rewrite your app to use these improvements. But here are a few tips:
1. Upgrade to .NET 10
Many of the GC improvements are automatic, so upgrading is the biggest step.
2. Tune GC if Needed
- Use Server GC (
<ServerGarbageCollection>true</ServerGarbageCollection>) for APIs and background services. - Use Workstation GC for desktop apps.
- Explore
GCHeapHardLimitandGCLatencyModefor fine-tuning in specific cases.
3. Monitor Memory
Use tools like:
dotnet-counters- dotMemory / PerfView
- Application Insights (in Azure)
4. Design for Memory Efficiency
Even with smarter GC, it’s good practice to:
- Reuse objects when possible (object pooling).
- Dispose unmanaged resources properly.
- Avoid creating massive short-lived objects unnecessarily.
Conclusion
The Garbage Collector in .NET 10 represents a significant leap forward. With smarter memory compaction, improved LOH handling, reduced fragmentation, better scaling for cloud environments, and shorter GC pauses, applications will run faster and consume less memory—with zero changes to your code.
For developers, this means:
- More predictable performance.
- Lower hosting costs.
- Happier end-users.
If you haven’t upgraded your apps to .NET 10 yet, now is the perfect time. Not only do you get the newest C# language features and BCL improvements, but you also get a world-class Garbage Collector working behind the scenes to make your applications shine.
Key Takeaway:
Upgrading to .NET 10 automatically gives you a faster, smarter Garbage Collector with better memory compaction. It’s one of the easiest ways to improve your app’s performance without touching a single line of code.