Why does my game hitch periodically?

Often garbage collection stutter: the runtime periodically pauses to reclaim memory, causing a hitch, and frequent allocations trigger this more often. If your game allocates a lot, especially per-frame or in hot paths, it generates constant garbage that forces frequent GC pauses, appearing as periodic frame-time spikes. The allocations may be hidden (in library calls, string operations, or boxing). Capturing frame-time spikes from real sessions helps you recognize the GC-driven hitches, which point at reducing allocations as the fix.

How do I reduce garbage collection stutter?

Reduce allocations, especially per-frame: avoid allocating in hot paths and code that runs every frame, reuse objects through pooling instead of creating and discarding them, avoid hidden allocations (string concatenation, boxing, some library calls) in frequent code, and minimize garbage generation overall. Fewer allocations mean the GC runs less often and pauses the game less, reducing the stutter. Capturing frame-time spikes lets you confirm GC stutter and verify that reducing allocations actually smoothed it out.

What Causes Garbage Collection Stutter?

Q: What causes garbage collection stutter?

Garbage collection (GC) stutter comes from the runtime periodically pausing your game to reclaim unused memory, and frequent, stutter-causing GC is triggered by allocation. The causes are frequent allocations (creating 'garbage'), per-frame allocations (in code running every frame), temporary short-lived objects, hidden allocations (from operations like string concatenation or boxing you don't realize allocate), and a large managed heap (taking longer to collect). The more garbage you create, the more often the GC runs and pauses the game, producing the stutter.

Quick answer: Garbage collection stutter comes from the runtime pausing your game to reclaim memory, triggered by frequent allocations. The cause is allocating too much per frame, forcing GC pauses that block the frame. Reducing allocations reduces it.

Garbage collection stutter, periodic hitches caused by the memory system, is a common performance problem in managed languages and engines. It has a specific, addressable cause. Here's what causes garbage collection stutter.

How GC Causes Stutter

In managed environments, the garbage collector periodically reclaims memory no longer in use, and doing so often pauses your game briefly, causing a hitch. What triggers frequent, stutter-causing GC is allocation.

Frequent allocations, allocating lots of memory (creating 'garbage') triggers GC more often
Per-frame allocations, allocating in code that runs every frame, generating constant garbage
Temporary objects, creating short-lived objects that immediately become garbage
Hidden allocations, allocations from operations you don't realize allocate (some library calls, string operations, boxing)
Large heap, a big managed heap taking longer to collect, causing bigger pauses

The more garbage you create (through allocations), the more often the GC runs, and each run can pause the game, producing the stutter.

Why It's Often Hidden

GC stutter can be hard to trace because the allocations causing it may be hidden, in library calls, string operations, or boxing you don't realize allocate. And the stutter appears as frame-time spikes that you have to look for, since average FPS hides them.

Bugnet's performance snapshots capture frame-time spikes from real sessions, so the hitches GC causes surface in your data. Capturing the spikes is the first step to recognizing GC stutter, which then points at reducing allocations.

Reducing GC Stutter

Reducing GC stutter means reducing allocations, especially per-frame: avoid allocating in hot paths, reuse objects (pooling) instead of creating and discarding them, avoid hidden allocations (string concatenation, boxing) in frequent code, and minimize garbage generation. Fewer allocations mean less frequent GC and less stutter.

Bugnet captures the frame-time spikes GC causes, so you can confirm the stutter and verify reductions. So garbage collection stutter comes from frequent allocations triggering GC pauses, and reducing it means cutting allocations, especially per-frame, through reuse and avoiding hidden garbage.

GC stutter comes from frequent allocations triggering garbage-collection pauses that block the frame. The cause is allocating too much, especially per-frame. Reduce allocations through reuse and avoiding hidden garbage to reduce it.