Space Marine 2 Lag Fix After Purgation Patch 13: Shader Cache, VRAM, and the Real Bottleneck

Warhammer 40,000: Space Marine 2 renders hundreds of Tyranids on screen simultaneously, and the Swarm Engine handles that workload differently from almost every other shooter on the market. GPU utilization at 1080p Ultra sits around 53% on many systems. The remaining frame time goes to CPU-bound tasks: enemy AI pathfinding, cloth simulation, physics calculations, and particle effects. That CPU bottleneck is why Space Marine 2 stutters in ways that standard “lower your graphics” advice rarely fixes, and it’s why this Space Marine 2 lag fix guide focuses on the settings most optimization articles skip.

The Purgation update (Patch 13) made things worse for some players, introducing shader compilation hitches and frame rate drops from 80 FPS down to the low 40s in Chaos zones. Here’s what actually works.

What Purgation Patch 13 Changed

Patch 13 added a new PvE Operation set in the Kadaku swamps, a complete Siege Mode overhaul with Hive Tyrant and Mutalith Vortex Beast bosses, the Battle Simulator practice arena, and weapon balance passes across nearly every firearm class. Bolter non-headshot damage went up roughly 30%. The Plasma Incinerator’s common shot damage increased 40%. Class perk scaling changed across Techmarine, Heavy, and Sniper builds.

The content is substantial, but the patch also triggered shader recompilation on many systems. DirectX 12 games cache compiled shaders locally, and a major patch invalidates parts of that cache. The result: the first few sessions after updating stutter every time the engine compiles a new shader variant, particularly in areas with new particle effects or lighting conditions. This is temporary if you let the cache rebuild, but permanent if you keep clearing it at the wrong time.

Hotfix 13.1 followed shortly after, restoring Gunstrike damage to pre-13.0 values and fixing several crash reports. Install it before troubleshooting further.

Clearing and Rebuilding the Shader Cache

The post-patch shader stutter is the single most common complaint on the Steam community forums. The fix is counterintuitive: clear the old cache once, then leave it alone.

Step 1: Close Space Marine 2 completely.

Step 2: Delete the local shader cache folder:

%localappdata%\Saber\Space Marine 2\client\local_shader_cache

Step 3: For NVIDIA users, also clear the driver-level DX cache:

C:\Users\%USERNAME%\AppData\LocalLow\NVIDIA\PerDriverVersion\DXCache

For AMD users, clear the cache at:

C:\Users\%USERNAME%\AppData\Local\AMD\DxcCache

Step 4: In NVIDIA Control Panel, set Shader Cache Size to Unlimited under Manage 3D Settings. This prevents the cache from being evicted prematurely, which forces recompilation and causes the same stutter to repeat every session.

Step 5: Launch the game and play through one full Operation without quitting. The first 10 to 15 minutes will stutter as shaders compile. After that initial session, the cache stabilizes and subsequent launches run smooth.

Do not clear the cache again unless you update your GPU driver or another major patch drops. Clearing it repeatedly traps you in the recompilation cycle.

Graphics Settings That Target the CPU Bottleneck

Most guides focus on GPU-heavy settings like shadow quality and ray tracing. In Space Marine 2, the biggest frame rate gains come from reducing CPU workload. Saber’s official troubleshooting page addresses some of these, but the community has identified additional settings that matter.

Volumetrics: This is the highest-impact CPU setting. Volumetric fog and smoke require per-frame calculations for light scattering across hundreds of particle sources. Dropping Volumetrics from Ultra to Medium can recover 10 to 15 FPS during swarm encounters without a dramatic visual difference.

Cloth Simulation: Every Space Marine cape, banner, and Tyranid membrane runs cloth physics on the CPU. Setting this to Low saves meaningful frame time in co-op sessions where three players with full cosmetic loadouts fight 200+ enemies at once.

Effects Quality: Explosions, Pyreblaster flames, and Plasma Incinerator impacts are all CPU-driven particle workloads. Medium is the sweet spot between visual quality and frame budget.

Ray Tracing: Disable it. SM2’s implementation offers minimal visual improvement while consuming both GPU and CPU resources. The game’s baked lighting already looks excellent.

Texture Resolution: The “High” preset is a known problem. Players with 8 GB VRAM cards (RTX 3070, RX 6800 XT) report micro-stuttering on High that disappears on either Medium or Ultra. This appears to be a streaming bug specific to the High preset. If you have 8+ GB VRAM, use Ultra. If you have 6 GB, use Medium. Skip High entirely.

Upscaling: Enable DLSS (NVIDIA) or FSR (AMD) at Quality mode. Space Marine 2 does not support frame generation, so upscaling is your primary tool for pushing frame rates above your native resolution baseline. For a broader look at GPU driver settings that affect all games, our driver guide covers the full process.

If your co-op sessions still spike after optimizing local settings, the problem might sit between your PC and the game server rather than inside your rig.

VRAM, Texture Streaming, and the SSD Requirement

Space Marine 2’s texture streaming system is storage-speed dependent. The game loads textures on demand as you move through levels, and a mechanical hard drive (or even a slow SATA SSD) cannot feed data fast enough to prevent pop-in and micro-stutter. Saber Interactive lists an SSD as a hard requirement, not a recommendation. If you installed SM2 on a spinning disk to save space, move it to an NVMe drive first.

If the game lives on an NVMe drive and you still see texture pop-in, check VRAM usage with a monitoring overlay. SM2 is aggressive with VRAM allocation: players report usage climbing past 14 GB during extended sessions on Ultra settings. On cards with 8 GB VRAM, the engine constantly swaps textures between VRAM and system RAM, producing hitches during fast camera movement or area transitions.

Enable Resizable BAR (ReBAR): If your motherboard and GPU support it, enabling ReBAR in BIOS reduces micro-stutter in SM2’s texture-streaming environments. ReBAR allows the CPU to access the GPU’s full VRAM pool directly, eliminating the small transfer window that causes streaming bottlenecks. Check your motherboard manufacturer’s support page for BIOS update instructions specific to your board.

Set a large pagefile: Running 16 GB of system RAM (the recommended spec) can be tight during SM2’s peak memory usage. Set your pagefile to at least 32 GB on your SSD. Multiple players on the Steam forums report that 64 GB eliminated late-session crashes entirely.

Multiplayer Connection Fixes

Space Marine 2’s online infrastructure has been rough since launch. Players report that matchmaking frequently fails (the loading screen loops back to the Battle Barge), and successful connections often suffer from rubberbanding during swarm encounters. The Purgation update’s new Kadaku swamp Operation and revamped Siege Mode mean more online traffic, which makes stable connections more important than ever.

Port forwarding: SM2 uses Steam’s networking layer. Forward the standard Steam ports in your router to ensure your connection to game servers isn’t blocked or throttled by your router’s NAT.

Crossplay settings: If you’re on PC and queuing into mixed-platform lobbies, try disabling crossplay temporarily. Some matchmaking failures stem from the crossplay relay layer rather than the core netcode.

Close bandwidth-heavy background apps: Discord screen sharing, streaming overlays, and Windows Update downloads all compete for upstream bandwidth during co-op sessions. Closing them before queuing reduces packet loss and desync. For the full list of processes worth killing before gaming, see our background process guide.

ISP routing: SM2 doesn’t expose a server browser. Matchmaking prefers nearby servers, but your ISP may route traffic through congested nodes during peak hours. A game traffic optimizer can bypass those nodes and connect you through a cleaner path.

Windows and Driver Cleanup

Clean GPU driver install: If you recently updated Windows and noticed new stuttering, your driver may need a full reinstall. Download Display Driver Uninstaller (DDU), boot into Safe Mode, remove the old driver completely, then install the latest Game Ready (NVIDIA) or Adrenalin (AMD) version fresh. Saber’s official support specifically recommends this approach for post-update performance regressions.

Windows Game Mode: Leave it on. Despite mixed advice online, Game Mode prevents background tasks from stealing CPU time, which directly benefits a CPU-bottlenecked title like SM2. For additional Windows 11 gaming settings that apply across your whole library, we cover the full list.

Hardware-Accelerated GPU Scheduling (HAGS): Test with it both on and off. Results vary by GPU generation. RTX 30-series cards tend to benefit from HAGS; RTX 40-series results are mixed. Benchmark with it toggled and keep whichever setting yields smoother frame pacing in swarm encounters.

Fullscreen vs. Borderless: Saber recommends borderless windowed mode for players experiencing stutter in exclusive fullscreen. Some players report the opposite. If your current mode stutters, switch and test for a full Operation before making a judgment.

Local settings cover the FPS and stutter side of the problem. For the networking side of co-op lag, a dedicated game route makes a measurable difference in session stability.

Post-Purgation Checklist

If you just updated to Patch 13 and the game runs worse than before, work through this in order:

1. Install Hotfix 13.1.
2. Clear the local shader cache once (path above), then play a full Operation to rebuild it.
3. Set NVIDIA Shader Cache Size to Unlimited.
4. Drop Volumetrics, Cloth Simulation, and Effects to Medium.
5. Disable Ray Tracing.
6. Set Texture Resolution to Ultra (8+ GB VRAM) or Medium (6 GB VRAM). Skip the High preset.
7. Enable DLSS or FSR at Quality mode.
8. Enable ReBAR in BIOS if your hardware supports it.
9. Set your pagefile to at least 32 GB on an SSD.
10. Clean-install your GPU driver with DDU if Windows recently updated.
11. Forward Steam ports for multiplayer stability.
12. Close Discord screen sharing, streaming overlays, and Windows Update before queuing co-op.

Space Marine 2’s performance profile is unusual: most of the stutter comes from the CPU, not the GPU. Turning everything to Low misses the point. Target the CPU-bound settings, let the shader cache stabilize after a patch, handle the network layer for co-op separately, and the Purgation update’s content is absolutely worth the troubleshooting effort.