Your Game's GC Spikes? Blame Yourself.

Mastering Allocation-Free Data Processing with Span and Memory in Unity

Introduction

Tired of unpredictable stuttering and frustrating garbage collection (GC) spikes in your high-performance Unity game? Those erratic frame drops often stem from subtle, repeated memory allocations, even within performance-critical systems. While Unity’s Job System and Burst Compiler aim for allocation-free execution, common C# patterns can inadvertently introduce GC pressure. This tutorial will guide you through mastering Span<T> and Memory<T>, two powerful C# features indispensable for achieving truly allocation-free, Burst-compatible code, particularly when working with NativeArray<T> and unmanaged memory within Unity's Data-Oriented Technology Stack (DOTS).

Code Layout/Walkthrough: Eliminating GC Spikes with Zero-Allocation Views

A frequent culprit for GC spikes is the unnecessary creation of temporary arrays or sub-arrays. Functions that need to process a segment of a larger data block often resort to methods like Array.Copy or LINQ extensions like Skip().Take().ToArray(). While convenient, each of these operations allocates new memory on the heap. In a tight game loop or within high-frequency jobs, repeated allocations quickly accumulate, triggering the garbage collector and causing noticeable frame rate instability.