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QjackCtl Graph Window laggy with DrumGizmo in Ardour

When using the graph window to make connections it is usually responsive.

I loaded DrumGizmo into Ardour and this creates a lot of input/output ports and wires between them. The graph window is now unusably laggy. There is a delay between dragging a wire and the wire appearing. This gets progressively worse the higher the zoom setting. The more I zoom in the more laggy the graph window becomes.

I'm using Arch linux and QjackCtl 0.9.2

rncbc's picture

please resort to the old Connections window, if you please.

when there's lots and lots of ports or whatever, the Graph won't be really manageable or useful anyway. ;)


Thanks for your reply.

I like the Graph window in QjackCtl because I can change the colours of ports and use JACK pretty-names.

When I was investigating this I tried the patchbay in Carla at the same time as QjackCtl and the Carla patchbay can handle DrumGizmo without responsiveness decreasing. I also have had big projects in Carla e.g. 30 instances of a synth where QjackCtl was not laggy.

But yes, I can find workarounds.


I have the same problem, the Graph becomes laggy also when you open an Ardour project with few tracks. In the previous versions (like 1 year to few months ago) of Qjackctl i didn't notice this problem.
Hope this will be solved in the future.
Thank you.

rncbc's picture

hi, when you say that the Graph is lagging, may I ask what you really mean?

I've been testing--yes "testing", just because ardour is not quite my piece of cake, I think you understand--with several dozens of tracks on ardour6.6 and, quite frankly, I'm don't get what you're meaning :)

care to give some more details on your machine, setup and environment?
really appreciate that.

I tried on 2 different machines with very different HW on them, cheap Intel CPU vs expensive Intel CPU, Intel GPU vs Nvidia with proprietary drivers, no difference. The problem seems to be the presence of "curved" connections, like when you have more output connections coming back to inputs in the same client, like Ardour. When you have "straight" connections there is no noticeable lag, like you could have with a simple Carla setup, Ex: Synth > FX > Mixer > System Out.

rncbc's picture

care to tell what exactly you mean with "lagging" or "noticeable lag" ? is it about view refresh? delay in selecting or moving nodes? making connections or disconnections? what and when exactly, please.


By lag i mean an increased delay between the mouse click or drag and the movement of graph elements. For example when moving clients, selecting, creating or deleting connections, the delay seems directly proportional to the number of "curved" connections present in the client. If i disconnect all the "curved" connections the interaction with that client in the Graph becomes snappier again.
Thanks for taking time to look into this.

rncbc's picture

I see... but it also gets better on zooming out and worse on zooming in...

well, if you can't live with that, for the moment then my first reply still applies ;)


rncbc's picture

hi there, good news:

been listening to your concerns and then, duly investigated the wth was going on in there...

as it happens, in the long run and finally reaching the bottom line, just found that too-much eye-candy was causing this and some graphical diabetes type IV, perhaps (my nomenclature) ;)...

all is now mitigated on qjackctl >=

just don't worry too much about, uh, connection lines not having a dang drop-shadow effect anymore. good riddance!

[UPDATE:] forget the last line, drop-shadow eye-candy++ is back to connection lines. and the laggy behavior seems to be gone too.

please test && tell, thanks.


Thank you very much. :D

Thanks for working on this.

The lagginess is gone in 0.9.3 and it's possible to zoom in without lagginess.

The colours of wires are now behaving differently. I have set my ports to an orangey/yellow colour and when I grab a wire and extend it all the wires underneath the pointer go white. In 0.9.2 this highlighting of wires was good as it showed what was connected to what. Now the highlighting seems a bit random.

Thanks for tracking the issue down!

rncbc's picture


the highlighting here is as it were before, no more no less, than the highlight color from current color theme.


Had a bit of a problem with a screenshot. When changing focus to the screenshot app QjackCtl lost the highlighting, but I think this shows that the graph window isn't behaving as expected :

File attachments: 
rncbc's picture

well, it looks like it is exactly behaving as expected though...

on (very) dark color themes--say, almost black, as you seem to be showing in the provided screenshot--the drop-shadow to each connection line is a white shade (would be black otherwise); what you're seeing (and I see too:)) is a bunch of a lot of dense connection lines that superimpose each and every other and it just, well, enhance the whiteness of the the aggregated white shading--faint white becomes whiter and whiter... get it?

on the other note, as kindly said before, don't count on Graph to manage ardour connections; those should be managed inside ardour premises anyway.

you may just move that whole awful spaghetti away to some far and hidden side, and then just painlessly deal with the other little fellows in the center of the Graph ;)

my 2c. of course

Not like spaghetti, eh?

Compared to some analogue studios I've been in that is not a lot of spaghetti. :) I'm familiar with making connections this way and prefer the look of it to the matrix approach of Ardour's connections window.

I'll attempt another screenshot -- I may have to take a photo on my phone.

So let's say it wasn't Ardour. I'll describe the behaviour more generally. When moving the pointer around wires are highlighted. Many wires turn white. In what I remember of 0.9.2 if I clicked on a port only the wire or wires connected to that port turned white, showing what is connected. Now in 0.9.3 the wires that have turned white stay white. When I took a screenshot the graph window changed to the 'correct' view -- one white wire amongst many orangey ones.

I should add that this is not a huge issue but the highlighting made my spaghetti more manageable in 0.9.2

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