GRBL look ahead not working

[Chai (Omer)]

I just built myself a little laser engraver to play with. I used whatever I had under hand, so ended up with GRBL on an Uno and a CNC shield left from a project from years ago, currently using the trial on Lightburn.

Now to the problem: when scanning, the G-code looks fine, a single line looks like this (incremental movement):

G1 X-1.25
G1 X-3.2S600
G1 X-13S0
G1 X-2.4S600
G1 X-0.7S0
G1 X-1.1S600
G1 X-1.25S0
G1 X-0.5Y0.1

Given this G-code I would expect one constant speed movement with the laser flickering, but I can see and hear accelerations from the motors. Laser mode is enabled.
I know GRBL is no longer being updated, but I was under the impression this shouldn’t be a problem. Any advice would be appreciated.

[Dskall (D Kallenberger)]

I would say your acceleration settings are low then.

[Chai (Omer)]

Might be, but why is there acceleration in the first place? The machine shouldn’t attempt to stop.

[Chai (Omer)]

For the sake of anyone who might be looking at this in the future:
The problem was I was running the laser at 5000 mm/min, and apparently emptying the buffer. Reducing the feed to 2500 mm/min solved the problem and faster work will probably require a better controller board.