Step-by-step per-sim FPS tuning

These notes summarise what to check inside each sim before blaming RaceLab overlays. Always begin with in-game graphics optimisation, then confirm telemetry and overlay setup.

iRacing

Optimise CPU threads & mirrors

  1. Turn off crowds, pit objects and extra shadows first – largest FPS wins.[1]
  2. In Options → Graphics, lower mirrors count and Max Cars visible.
  3. Prefer Fullscreen or Borderless window when using RaceLab overlays.
  4. Cap FPS to monitor refresh; iRacing runs smoother with frame pacing under control.

Tip: if overlays vanish after alt-tabbing, switch to borderless mode and relaunch RaceLab.

LMU

Handle lighting & reflections

  1. Reduce Reflections and Shadows to High or Medium for big GPU savings.[2]
  2. Disable HDR if triple-screen projection causes heavy frame loss.
  3. Use Borderless window – ensures overlays align correctly.
  4. Check RaceLab UDP port (default depending on config) – keep it unique per app to avoid telemetry delay.
ACC

Unreal Engine tweaks

  1. Lower Shadows, Foliage, and Post-processing first.[3]
  2. Disable Motion Blur and reduce Temporal AA sharpening for VR stability.
  3. Test V-Sync both on and off; frame caps can smooth stutter in rain/night.
  4. Keep overlays simple – heavy animated ones can add latency through UE4’s render pipeline.
rFactor 2

Thread balancing & overlays

  1. Lower Visible Opponents to 20–25 for full grids.[4]
  2. Keep Reflections on Low and reduce Environment to Medium.
  3. Restart the sim after long sessions to release VRAM.
  4. Confirm RaceLab plugin path → rFactor2\Bin64\Plugins and correct telemetry port.
AMS 2

Madness Engine load control

  1. Use a High preset, then drop Reflections and Weather to Medium.
  2. Prefer MSAA ×2 or FXAA for triples – higher levels can cause shimmer and stutter.
  3. RaceLab overlays are very light – main bottleneck is GPU shading.
  4. When streaming, cap at around 90 FPS for smoother frame pacing.
F1 2024 / 2025

DX12 tuning & UDP check

  1. Disable Ray-tracing on mid-range GPUs – large FPS gain.[5]
  2. Use Borderless instead of Fullscreen for stable overlays.
  3. Verify UDP telemetry format/port in-game matches RaceLab configuration.
  4. Lock to 60 FPS when streaming or on multi-display setups.

Sources & References

  1. iRacing community FPS and RaceLab overlay integration threads. ↩ back
  2. Le Mans Ultimate forum notes on HDR, reflections and telemetry UDP setup. ↩ back
  3. Assetto Corsa Competizione Unreal Engine performance guides and VR tips. ↩ back
  4. rFactor 2 graphics optimisation posts and RaceLab plugin configuration. ↩ back
  5. F1 series technical documentation for DX12 rendering and UDP telemetry options. ↩ back