In Game Features

In-Game Features & Control Center

When the Project Zomboid Optimiser Steam Workshop Mod is subscribed alongside the PZO Launcher or Java Engine, it unlocks real-time in-game configuration, telemetry dashboards, and visual engine health indicators.

---

Main Menu Engine Status Indicator

Located in the top-right corner of the main menu:

• Active Status: Displays the PZO gear icon in full color. Hovering reveals the tooltip: "PZO Engine Active".
• Inactive Status: Displays a muted icon. Hovering reveals: "PZO Engine Inactive".
• Click Interaction: Clicking the icon provides quick diagnostic information on whether the native C++ library (pzo_native64.dll / libpzo_native64.so) and Java agent are attached.

---

First-Entry Multithreading Notice Modal

On the first game boot after installing PZO, an informative modal dialog appears:

• Purpose: Explains that Build 42 multithreading, chunk streaming, and memory caching optimizations are active.
• Compatibility Notice: Confirms full compatibility with third-party Java mods (such as ZombieBuddy) and Workshop mods.
• Direct Links: Provides quick buttons to view the Steam Workshop page and GitHub source repository.
• Acknowledgment: Clicking "Understood" dismisses the modal and saves the preference to pzo_ack.txt, preventing it from appearing again on subsequent launches.

---

In-Game F10 Control Center

Pressing F10 at any time during gameplay toggles the floating PZO Optimization Dashboard. The interface is divided into seven dedicated tabs:

Tab 1: Performance Presets & Thread Allocator

• One-Click Presets:
  • Balanced: Recommended for standard 4-8 core CPUs.
  • High Performance: Allocates maximum parallel workers for 8-16+ core CPUs.
  • Battery Saver / Low-End: Throttles background task workers for laptops and handhelds (Steam Deck).
• Worker Thread Sizing: Dynamically re-assigns CPU threads allocated to background pathfinding, chunk loading, and physics updates.

Tab 2: Chunk Streamer & Map Caching

• Deep RAM Chunk Cache: Keeps visited map chunks cached in off-heap direct memory rather than constantly re-reading from disk.
• High-Speed Vehicle Travel Streamer: Automatically ramps up chunk loading priority when driving vehicles at high speeds, preventing vehicle black voids and sudden tree collisions.

Tab 3: Zombie Simulation & Distance Hibernation

• Spatial Distance Hibernation: Suspends expensive pathfinding and collision calculations for zombies located beyond player sightlines.
• Horde Migration Throttler: Smooths out zombie population redistribution to avoid micro-stutters when entering high-density urban areas.

Tab 4: Audio & Corpse Governors

• Corpse Audio Throttling: Limits redundant sound emitter calculations when hundreds of zombies are killed in dense piles.
• Corpse Visual Culling: Optimizes skeletal mesh animation updates for distant deceased bodies.

Tab 5: Garbage Collector & Memory Cleaner

• Generational Heap Governor: Monitors heap pressure and schedules incremental memory cleanups during idle moments (e.g. reading, sleeping, waiting).
• Manual Trim Memory: Instantly triggers an off-heap direct memory compaction and hint to the HotSpot JVM.

Tab 6: Hardware Acceleration & Frame Pacer

• High-Precision Timer: Toggles OS multimedia timer frequency between stock Windows (15.6ms) and high-precision mode (1.0ms).
• Frame Pacing Synchronizer: Eliminates micro-stutters caused by fluctuating tick delta calculations.

Tab 7: [+] JVM Engine & Live Telemetry

Only active when PZOptimEngine.jar is attached via -javaagent.

• Real-Time FPS & Frame Time: Graphs millisecond frame delivery times.
• JVM Heap Usage: Visual gauge displaying current megabytes allocated, committed, and max heap.
• GC Pause Time Monitor: Displays the duration of the most recent Garbage Collection pause in milliseconds.
• Active Threads: Monitors live thread count across the Zomboid process.
• Engine Architecture Status: Displays status of bytecode hooks, native C++ DLL bindings, and JIT compiler flags.

---

Telemetry Files

PZO streams telemetry to small JSON files in the user's Zomboid/Lua/ directory for integration with overlays, performance monitors, or external dashboards:

• pzo_status.json: Engine attachment state, active version, and architecture.
• pzo_telemetry.json: Client FPS, frame times, heap memory, and GC pause metrics.
• pzo_render_telemetry.json: Render pipeline and FBO draw call metrics.
• pzo_server_telemetry.json: Dedicated server TPS, heap, threads, and host CPU utilization.