Bug report – Severe lag / delayed start when engraving images on Fiber Galvo in LightBurn versions newer than 1.7.08

Hello!

I’d like to report an issue (possible bug) that I’m consistently experiencing in LightBurn versions newer than 1.7.08, related to image engraving on a Fiber Galvo laser.

Setup

  • Laser: JPT MOPA M7 – 20W

  • Material: Photo engraving (grayscale images)

  • LightBurn versions tested:

    • :white_check_mark: 1.7.08 – works perfectly

    • :cross_mark: Newer versions (including 2.0.05) – problem occurs

Engraving settings (identical in all versions)

  • Mode: Grayscale

  • Power: 22%

  • Speed: 900 mm/s

  • Line Interval: 0.02 mm

  • Q-Pulse: 200

  • Frequency: 1200 kHz


What works correctly (LightBurn 1.7.08)

  • After pressing Start, engraving begins almost instantly

  • Galvo movement is fast, smooth, and continuous

  • Engraving result is perfect and correctly aligned


What happens in newer LightBurn versions

Using exactly the same file and settings:

  1. After pressing Start, there is a 5–8 minute delay before the laser actually starts engraving

  2. When engraving finally begins:

    • Galvo movement is very slow and jerky

    • Motion feels laggy / stuttering

  3. The final engraving shows a large positional offset, similar to:

    • CO₂ + Ruida photo engravings when the image file is extremely large or processing is delayed

Troubleshooting already done

  • Fully uninstalled LightBurn (manual cleanup)

  • Reinstalled newer LightBurn versions (e.g. 2.0.05)

  • Reinstalled Galvo drivers

  • Tested on:

    • Another Windows PC

    • macOS

  • Result: exact same behavior on all systems

:warning: Important note:
As soon as I reinstall LightBurn 1.7.08, everything works perfectly again with no lag or delay.


Additional observation

I’ve also noticed similar lag behavior on CO₂ lasers with Ruida controllers when engraving photos in newer LightBurn versions, using the same settings that work fine in 1.7.08.


Experience

I’ve been using LightBurn since its early days, and this is the first time I’ve encountered such a major regression related to image engraving performance.