Gantt software started lagging while using Apple M1


I installed Azul zulu 11.45.27, but no help GP3 and GP2 is still lagging. If i zoom out my project then it is running ok (i can use it properly), but if i zoom in it starts lagging heavily and its hard to use. Is there any work around I could try?


Can you please share the project file? Maybe it is not M1 which is the issue.

laging project.gan (18.9 KB)

This is the one. As i said, when zoom’ed out seems ok, but when i zoom in gantt, than lagg starts. Thanks!

Do you have any kind of update?

I tried playing with this file on my Linux and it was okay, so most likely the issue is either with JRE+M1 or with something else on your Mac environment.

I noticed that on my second screen it works great, but one my main laptop screen it does not… I have a video, but I cannot attach it here…

You can upload a video on YouTube or ZIP it and attach the archive here.

Hello there,

I attached the video to wetransfer.

What happens if you scroll using navigation buttons above the chart, “Past” and “Future”? Is the behavior the same?

Yes, it acts the same.

It seems that there is BellSoft Liberica Java 11 Runtime with JavaFX for M1. You can try installing it and running GanttProject ZIP distro.

I also have performance issues with GanttProject on my Apple M1. Unfortunately, using BellSoft’s JRE doesn’t seem to change much.

I did the following:

After this, in the Activity Monitor I can confirm that GanttProject now runs on ‘Apple’ instead of ‘Intel’ (column ‘Kind’). However, as mentioned above, with similar performance as before.

Some notes:

  • Performance seems to have improved upgrading to 3.2.3240.
  • First time you might need to go to System Preferences, Security & Privacy to allow java to run.
  • I get one error when starting (printed to the console): InteropFactory: cannot load com.sun.javafx.embed.swing.newimpl.InteropFactoryN, not sure if this matters.
  • Poor performance means, on the default ‘House Building’ project, that sometimes it takes 2-3 seconds when I click for the open hand to become closed (to scroll left/right), I regularly get the colour wheel, and some actions that I would assume easy take several seconds. On a more complex project, things get worse.
  • See Download OpenJDK builds of Liberica JDK, Java 8, 11, 17, 18 | BellSoft Java for all BellSoft’s options.

Can you please send signal QUIT to java process while GanttProject is thinking (with kill -3 [process id])? It will print a lot of stuff to the console, please send it to me. It is better to send QUIT a few times. I think you can redirect the console output to a file with tee command.

Hi @DmitryBarashev

I’ve followed the steps @dloeckx mentioned to see if I had the same issue. I can confirm that it also runs natively (as can be seen in the Kind column of Activity Monitor) and the lagging issues persist.

I sent the kill signal to the Java process as you mentioned and have attached the debug output. Hope this helps!

ganttproject-java-kill-out-mac-m1.txt (30.7 KB)

Thanks. Was it produced when GanttProject was thinking?
Also, did you notice high CPU usage?

also, can you please try running GP with Java 17 runtime, as described in this post?

I’m not sure what defines “thinking” here but when trying to scroll left & right in a project that has 9 items in I see the CPU usage go from 44% to over 100%. Scrolling left & right works without any lag in an empty project if that helps.

I tested the above with both Java 11 and Java 17 and see similar CPU usage spikes.

Let me know if there’s anything more I can provide to help diagnose these issues

So, did you send kill -3 exactly at the moment when CPU usage was high?

I’m not sure so I’ve reproduced the kill -3 message using both Java 11 & 17 when CPU usage goes over 100% in Activity Monitor. Find files attached below.

ganttproject_java-11_kill-3-high-cpu_mac-m1_out.txt (27.0 KB)
ganttproject_java-17_kill-3-high-cpu_mac-m1_out.txt (30.7 KB)