What if I told you that starting with .NET 10, several of your fundamental ideas about garbage collection are now outdated? Imagine that there are actual improvements that can sometimes cause two to three times better memory usage and speed. These improvements are available through a series of runtime switches and new optimization behaviors. However, it is important to consider that these improvements come with trade-offs that you need to evaluate instead of simply enabling them on faith.
In this post, I’ll take you through the real story in .NET 10, show you the rationale behind the new GC features, give you actionable patterns, code, and measurement tools, and help you answer: should you rely on these improvements or tune and even disable them for your scenario?
Fundamentals of .NET Garbage Collection
Since the dawn of the CLR, .NET’s memory management model has used a generational, tracing garbage collector. This model means all object allocations live on a managed heap, with the GC tracking which objects are still “in use” (reachable from application roots) and which can be reclaimed.
The GC splits heap memory into:
Generation 0 : the youngest objects, collected most frequently.
: the youngest objects, collected most frequently. Generation 1 : survivors promoted from Gen 0, acting as a buffer.
: survivors promoted from Gen 0, acting as a buffer. Generation 2 : long-lived survivors—think caches, statics, or persistent models.
: long-lived survivors—think caches, statics, or persistent models. Large Object Heap (LOH/”Gen 3″): for objects >85 KB, managed specially to avoid frequent compaction.
Why generations? Because most objects die young. Focusing collections on Gen 0 means low overhead, fewer full-heap pauses, and better cache locality.
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