Core Performance & Telemetry

Core Performance & Telemetry – RaceLab

Core Performance & Telemetry

This page covers the two things that decide whether RaceLab “feels smooth”: performance (FPS / stutters) and telemetry (data reaching RaceLab). [1]
Important (Pro vs Free): Layout editing / saved layouts are Pro-only. Telemetry and basic overlay visibility are separate from that. If you’re not Pro, focus on the checks below (do not worry about layout editor features). [2]
Fast Fix Ladder Performance Basics Telemetry Basics Ports & Firewalls Symptoms → Fix What to Send Support Sources

Fast Fix Ladder (Do these in order)

  1. Restart clean: Close sim → close RaceLab → restart PC → open RaceLab → open sim.
  2. Run one overlay only (test with the simplest overlay first). [1]
  3. Confirm telemetry is active: join a session (not just menus) before judging “no data.” [1]
  4. Disable other overlay tools temporarily (anything else drawing on top of the game) to test conflicts. [3]
  5. Firewall test: allow RaceLab through Windows Firewall (Private + Public) and test again. [4]
Rule: Don’t change 10 things at once. Change one thing, test, then continue.

Performance Basics (Smooth overlays)

What causes stutter?

  • Overlay count too high (especially animated widgets / heavy tables).
  • CPU spikes (browser sources, background apps, capture software).
  • GPU saturation (game maxed out + overlay rendering + streaming).
  • Window mode conflicts (exclusive fullscreen + overlays + capture). [3]

Quick stabilisers

  1. Use Borderless Window (often more stable with overlays/capture).
  2. Cap FPS (in-game or driver) so you don’t run at 99% GPU all the time.
  3. Reduce overlay update intensity: fewer overlays, smaller widgets, fewer tables.
  4. Close heavy background apps (browser tabs, RGB tools, video encoders you’re not using).
Simple test: If the game is smooth with RaceLab closed, then stutters appear only when RaceLab is open, it’s usually overlay load or a hook/capture conflict. [3]

Telemetry Basics (Data getting to RaceLab)

RaceLab reads game data either via a plugin (installed into the game folder) or via UDP telemetry (game sends data over the network). The exact method depends on the sim. [1]

Quick checks

  1. Confirm you selected the correct sim inside RaceLab (not a different sim’s mode).
  2. Join an active session so the sim is actually outputting telemetry.
  3. If that sim uses a plugin: confirm the plugin file exists in the correct folder.
  4. If that sim uses UDP: confirm the sim is configured to send data to your PC.
Common trap: “Telemetry is broken” when you’re still in menus, replays, or a mode that doesn’t output data. Test in a live session first. [1]

Ports & Firewalls (The boring stuff that breaks everything)

Problem What it looks like Fix
Windows Firewall blocked Overlays show but data is blank / no updates Allow RaceLab in Firewall (Private + Public). Then retest. [4]
Port already in use Telemetry/bridge won’t start, or features fail randomly Close other tools that use telemetry/UDP/web dashboards. Reboot and test one tool at a time. [5]
Wrong destination IP UDP telemetry enabled but RaceLab sees nothing Set the sim’s UDP destination to your PC’s IP (or 127.0.0.1 if the sim expects local). [6]
VPN / multiple adapters Data drops in/out or never arrives Disable VPN temporarily; prefer the active adapter; retest. [6]
Best practice: For testing, keep it simple: one PC, no VPN, one sim, RaceLab only. Once stable, add streaming/capture/extra tools back one by one.

Symptoms → Fix

1) “Overlays appear but don’t update / show blanks”

  1. Join a live session (telemetry must be active). [1]
  2. Firewall allow RaceLab (Private + Public). [4]
  3. Close any other telemetry tool temporarily (SimHub, dashboards, browser telemetry pages) and retest. [5]

2) “RaceLab makes the game stutter”

  1. Test with one overlay only. [1]
  2. Switch to Borderless Window and cap FPS. [3]
  3. Lower overlay load (fewer tables/animations). [3]

3) “It worked yesterday, now nothing works”

  1. Re-run the sim’s setup/configure step inside RaceLab (if available). [1]
  2. Check game updates didn’t remove a plugin file (plugin-based sims). [1]
  3. Do a clean reboot and test one overlay. [1]
Important: If you are a Free user, avoid troubleshooting “layout saving/editing” issues — that is Pro-only. Focus on telemetry + basic overlay visibility. [2]

What to Send Support (so it can be solved fast)

  1. Sim: (LMU / iRacing / ACC / etc.)
  2. RaceLab version: (exact number)
  3. Windows version: (Win10/11)
  4. What you see: “Overlays show but blank” / “No overlays” / “Stutter when RaceLab open”
  5. Test result: “One overlay only” test pass/fail
  6. Network: VPN on/off, single PC or multi-PC
Fastest reproduction: “Fresh boot → open RaceLab → open sim → join session → enable one overlay → result.”

Sources & References

  1. General RaceLab telemetry behaviour: sims output data either via plugin or UDP; telemetry often only becomes active in a live session. ↩ back
  2. RaceLab subscription model: Layout editor / saved layouts are Pro-only; telemetry and basic overlay visibility are separate concerns. ↩ back
  3. Common overlay stability principles: borderless window, FPS caps, reducing overlay load, and avoiding multiple overlay hooks at once. ↩ back
  4. Windows Firewall impact on local/network telemetry: blocked apps can receive no data until allowed. ↩ back
  5. Port/tool conflicts: multiple telemetry tools can collide; isolate by running one at a time. ↩ back
  6. UDP routing basics: correct destination IP / adapter selection and VPN effects. ↩ back
Unofficial support page maintained by Scottozy. Information is provided in good faith and may change as RaceLab and sims are updated.