GPU / CPU Tuning – Sim Racing & RaceLab
This page is about practical tuning for sim racing: getting your CPU, GPU, drivers and overlays working together so iRacing, LMU, ACC and other sims stay smooth even with RaceLab running.
- Prepare Windows and your drivers so they don’t silently throttle performance.
- Use game-specific GPU profiles instead of random global tweaks.
- Understand whether you are CPU-limited or GPU-limited in real races.
- See how RaceLab overlays and streaming change the load on your system.
1. Get the PC into “race mode” first
- Use a High performance or similar power plan while racing.
- Close background apps that chew CPU, GPU or disk (cloud sync, browsers, launchers).
- Make sure the sim and RaceLab are both using the dedicated GPU (not integrated graphics on laptops).
- Keep drivers reasonably up to date, but avoid unstable beta builds unless you have a reason.
2. GPU setup for sims & overlays
- Create a per-game profile in NVIDIA / AMD control panel for each sim you use.
- Let the sim control most graphics options and V-Sync to start with.
- Use a sensible FPS cap slightly under your monitor refresh (for example 141 on a 144 Hz screen).
- Prefer Borderless window in many sims when using RaceLab overlays and OBS together.
3. CPU behaviour in real racing conditions
- Hotlaps are easy – grid starts, rain, night and AI are what really test the CPU.
- Big stutters when the lights go out usually mean a CPU bottleneck, not a GPU problem.
- Reducing opponent count, mirrors and replays often helps more than lowering resolution.
- Strong single-core performance still matters a lot in many sims.
4. RaceLab, streaming & “extra stuff”
- Each overlay, browser source or dashboard adds a little bit of CPU and GPU load.
- RaceLab itself is light, but multiple animated overlays plus OBS scenes can add up.
- Use hardware encoders (NVENC / AMD) for streaming instead of heavy CPU encoders if possible.
- Test with overlays off, then with just one core overlay, then with your full layout to see where FPS changes.
Use this page together with your PC Specs & Baseline Settings and Performance & FPS checklist. When helping users, you can link them here as “Step 2 – tuning” after they’ve shared their hardware specs.
Step-by-step GPU / CPU tuning for sims & RaceLab
Follow these steps after you know the user’s specs. Start with Windows “race mode”, then tune the GPU profile, check CPU vs GPU load, and finally adjust RaceLab overlays and streaming settings.
1. Put Windows into “race mode”
- Press Windows key and type “power plan” or “choose a power plan” and open it.[1]
- Select High performance, Ultimate performance, or the vendor’s gaming plan (AMD Ryzen High Performance, etc.).
- In Power & sleep, set the screen and sleep timers long enough so the PC doesn’t try to sleep mid-race.
- Open Task Manager (<Ctrl+Shift+Esc>) and close obvious heavy background apps: browsers with many tabs, game launchers, cloud sync, video editors.
- On laptops, confirm they are plugged in – many machines throttle heavily on battery power.
Tip: Ask users to keep a “race desktop” with only the sim, RaceLab, and (optionally) OBS or voice chat running.
2. Create a per-sim GPU profile
- Open NVIDIA Control Panel / AMD Software and go to the section for Program settings or Game profiles.[2]
- Add each sim you use (iRacing, LMU, ACC, rF2, AMS2, F1, etc.) as a separate profile.
- Set Power management to “Prefer maximum performance” (or the closest equivalent) for those sims.
- Leave Anti-Aliasing and V-Sync on “Let the application decide” as a safe starting point.
- Optional: set Texture filtering to “Performance” or “Quality” depending on GPU tier – don’t chase Ultra on basic hardware.
Tip: Keep a screenshot of a “known good” profile for one sim. You can send that image to users as an example layout.
3. Is the bottleneck CPU or GPU?
- Ask them to enable the sim’s performance or FPS graph if available (CPU/GPU bars, frame time graph).
- Alternatively, open Task Manager → Performance while they drive: watch one CPU core and GPU usage.
- If GPU is around 95–100% but CPU is moderate: they are GPU-limited – reduce graphics options first (AA, shadows, reflections, resolution).[3]
- If one CPU core is pegged near 100% while GPU is relaxed: they are CPU-limited – lower opponent count, mirrors, replays, shadows, and some physics-heavy options.
- Ask when FPS drops: grid start, rain, night, certain tracks. Those moments help you see what is stressing the system.
Tip: Explain the result in simple language: “your graphics card is the bottleneck” or “your CPU is the bottleneck” so users understand why you’re changing certain settings.
4. Tuning overlays, OBS & extras
- Test in three steps:
- Sim only (no overlays).
- Sim + RaceLab with one core overlay (Relative or Standings).
- Sim + full RaceLab layout + OBS / streaming.
- If FPS is fine without overlays but worse with full layout, remove or simplify the heaviest overlays first (big timing towers, animated widgets).
- In OBS, use NVENC / AMD hardware encoding instead of CPU x264 on mid-range CPUs.
- Cap FPS slightly below monitor refresh (e.g. 72/90/120 or 141 on 144 Hz) to keep frame times stable while streaming.
- Check that all RaceLab browser windows and OBS browser sources are running on the dedicated GPU, especially on laptops.
Tip: Save one OBS scene collection and RaceLab layout as a “performance-safe” setup that you know works well. You can share these as reference presets for users with similar hardware tiers.
Sources & references
- Windows and gaming documentation on using High performance / Ultimate performance power plans to avoid CPU throttling under load. ↩ back
- NVIDIA / AMD guidance on creating per-application 3D profiles and setting power management mode for games. ↩ back
- Sim-racing and PC tuning guides explaining CPU- vs GPU-limited situations using in-game graphs and Windows performance tools. ↩ back