MuseScore 3.6.0 AppImage in Ubuntu Studio 18.04 with KXStudio is very slow to open and does respond with enormous delays (like 30 seconds or so)

'Not the case here'. Do you mean you tested it on Ubuntu 18.04? It should not be that hard to test that, although it requires an install. Of course, I cannot test reproducibility on my own system (even though the problem is consistent on my own system). It should at least be tested on Ubuntu and preferably the same version 18.04. If that gives the same problem, that should say enough. If not, one may conclude that it is something special/extra that I have. But, the only special thing I have is that I use Ubuntu Studio 18.04 with KXStudio on top (the latter is not standard); maybe that causes it, I don't know, and it may indeed be something that not everyone uses, but everything else works perfectly fine with me, and, to be honest, I can hardly imagine that that causes it (but one never knows). I need KXStudio, because Ubuntu and also Ubuntu Studio are moving away from Jack, including support of fire wire sound cards (they don't support it any more).

@ 'Jojo'. Meaning? Happened only once? You don't know yet. Seems an assumption based on many Linux users who have not yet said, and I'm the only one who mentions this (yet). Of course I'm using Ubuntu Studio 18.04 and the App Image MS 3.6.0 is not out for such a long time. And many, like myself, tend to use the old one, if something is not working properly. Also, saying that I'm the only one and no-one else is having the problem (and saying there are many) is not very encouraging to even mention a problem (if that's the attitude). Anyway, I hope it can be solved on my system. I need Ubuntu Studio 18.04 with KXStudio on top. Can't switch. I tried many distributions and solutions; this is the only one that works flawlessly with my home-studio and virtual pipe organ setup (everything based on Jack and Firewire).

I can't do that. I really need Ubuntu Studio 18.04 (long term stable release). I tried upgrading before, including a fresh install, but then I don't have a sufficient working combination with KXStudio, because the latest version of Ubuntu moves too far away of the things I need (even KXStudio cannot make up for that then). So, it does not give me a stable complete working studio at the very least. So, I went back to the trusted Ubuntu Studio 18.04. I spend a lot of time in that and I'm therefore not willing to install my system to the latest version (it would mess up my studio). I did not try the latest version of Ubuntu with this App Image. But, I remind you that under the downloadable App Image (https://musescore.org/en/download) it says: "Suitable for all Linux distributions'. I don't make the claim. Musescore does. Has it been tested on Ubuntu Studio 18.04? Or does this assume 'all latest versions of Linux distributions?' Then it should say so.

It might. I might also go to great lengths to try it on my other PC, a Thinkpad laptop (I would then try the AppImage with Ubuntu Studio 18.04, without and with KXStudio ). But then again, if I can reproduce it there, I would still be the only one at the time being. Would you believe me then? Would that be enough? The only difference is that it would not be exactly comparable even, with my OS on the PC (where I have the problem), because on my PC I have ran many updates already (no upgrades) and I'm not sure the laptop will have that updates then already (probably not all of them). But I would suppose that this App Image should work well, independently from updates on the Linux distribution (if not it would be very hard to claim it would work on any distribution; then one should name versions).

Ok. 'It runs on' assumes works well, as supposed to, on any Linux distribution. If that is not what one can assume, I'd rather would like to know on which distributions and versions it is tested.

I know that distribution (of course). Like I said, I upgraded to it and also freshly installed it already once, but returned to a freshly 18.04 install, for reasons I mentioned. Took me a lot of time (to try to get it work with my studio; it didn't).

It is exactly the same issue I had in the beta version (the app-image I used first; 3.5.2?), which now has gone into production.

That's such a shame, because I really need it and desperately want to use it, but it prevents me from being able to use it now. It would keep me waiting most of the time; to the extend that it really is unworkable. I will try to do some more testing, but, if you are not willing to make chances to it, unless there are more (how many?), what's the use of it?

@Jojo. 'Of course we believe you'. Good. First I'll try it on my Thinkpad (which has yet another Linux distribution; leight weight). Then I'll try the other relevant distributions mentioned also (but from a demo install on USB).

I just tried it on my other 'machine', my laptop, which has the Linux distribution Xubuntu running, VERSION="20.04.1 LTS (Focal Fossa)" .
Same problems with slowness (even though I use Alsa now instead of Jack; I have an USB soundcard connected to my laptop; no firewire). So, the sound the sound system used makes no difference, nor does the distribution, so it seems. Seems like a repetition to me.

Who? Me or you? All I can tell is that on my PC it uses Linux 4.15.0-132-lowlatency x86_64 and on the laptop Linux 5.4.0-58-generic x86 64. Both are kernels used by Ubuntu, which the latter is originally derived from Debian (I think). That's the branch the distributions are from (Ubuntu). I suspect now that it is a problem on all Ubuntu distributions, but I haven tested any further yet. I have to make USB boot drives with the distributions installed on it. Later.

@larshenrikoern. Read from page 6. https://www.gertim.com/Ubuntu_Studio_with_KXstudio.odt
I use Ubuntu Studio, with KXStudio on top. The reason why I did that is that it routes everything through and to Jack and works superior (for my firewire studio setup with virtual pipe organ). Without it, it is almost impossible to get everything working (I also use Ardour, Audacity, MuseScore, GrandOrgue with my studio and they all have to be able to work together). I don't use JackQt to setup jack. I use Cadence (by KXStudio; they cut Qt out). I use Jackd2 indeed. It is not bridged like you said; KXStudio does that differently and offers more possibilities.
With KXStudio everything is bridged to Jack and there are several options to do that. See also: https://www.gertim.com/Cadence_Jack.mkv

Ok, maybe that's it, yes. MS version 3.2.3 indeed offers no such problems at all (the slowness problems). I've used that extensively. Ah, that's a shame. That will probably it then. Thank you all for all the effort.

Thank you very much for the hint. I will test further on this. I always have pulseaudio running as a bridge to Jack, but to be sure... Do you mean this (pulseaudio running as a bridge) or do you mean that one should use Pulseaudio in Musescore also, as a MS setting as well (that I haven't; I use Jack there in the I/O settings in MS, because I need it to connect to GrandOrgue to be able to make recordings from Musescore playback).
The problem appeared while pulseaudio was running (that is; pulseaudio bridged to Jack). I always have pulseaudio running, because I use YouTube a lot, and without Pulseaudio you have no internet sound, from the browser (Firefox).

@Jojo-Schmitz. It would be nice to know what causes it exactly, so it can be addressed well by the developers, either of the Debian derivatives or MS developers. Do you have a clue what the problem is? Is it the sound system. Is it about dependencies? About libraries? Right now, it could be anything, right? Any idea?

Thanks anyway. I highly appreciate your help and the time you take to read all this and respond. Thanks again.

@Larshenrikoern. By the way. I just tested it and I have exactly the same problems with Pulseaudio turned off alltogether in Cadence and having the settings in MuseScore fully on Jack (the three checkboxes checked in the MuseScore Jack settings); exactly the same problem of great delay. It does not seem to make any difference (on my system). Maybe I'll try Gentoo on my laptop once and see how that works. I never used it.

@Jojo-Schmitz. I think Mirabilos may have an idea. He's the one who added the MS 3.2 repository. You probably know him better than I. I'm not sure he is a developer, but I suppose he is.

Great! Germany, I recall. If so, I'm your 'neighbor'.

@larshenrikoern. Thanks for the suggestions. I'm not going to try pajackconnect right now. I'm afraid to mess up the KXStudio settings with that and that is working fine (I have no problems with routing PA to Jack; works fine all the time). I also have 'MS 3.2.3+dfsg1-4~ppa1804+1' native on my system (through a repository, PPA, by Mirabilos, I believe). That version works fine, but i need the plugins of BSG, which don't work on that version. I may try another development version again, but I recall they had comparable problems. I combined both and used the buggy versions (on my system) to add the cut backs and the tempo changes and go back and forth; quite a pain to use it that way (with all the delays). What you describe about Gentoo. I'm not ready to build/compile an operating system from scratch. It is enough trouble already. I'm having quite a stable system, which outperforms Mac/Windows now and has extremely low latency settings and is rock stable right now. I went through a lot of trouble to get there already and to keep it that way. Maybe on a separate machine. Thanks for your great response. Very useful. Highly appreciated as well.

Thank you for your response, but I more and more think it indeed has to do with what was mentioned earlier, because that seems to make sense with my recent test results so far. I mean, what was mentioned earlier; that Debian variants/forks, like Ubuntu based distributions, haven't updated something crucial yet and so those distributions still use, or are forced to use MS 3.2. There is a problem with it.
For example: I just tested the latest version of AVLinux (AVL-MXE-2020.12.03-xfce4) on my laptop and it has exactly the same problems as I mentioned earlier. The AV Linux also has the 3.2 version standardly installed in the distribution and that version works totally fine. AVLinux is also a Debian 'fork'/derivative, so it confirms what was mentioned before. It is yet very well possible that I'm the first, to mention it. I just test and ran into this. What you say, may sounds likely, but one simply does not know it for sure (it is an assumption). And, with this, we cannot assume. When I test, however, then I know it for sure and can exclude things. There may be a dozens of reasons why it has not been noticed or reported by others. I did it this time (for numerous reason that also may not apply to any one else). But, it can be significantly reproduced, so it seems, and that's all what matters. Because, the problem appeared not only on my PC, but also on my laptop, 2 times on 2 different OS's, with a totally different sound system as on my PC (but both are forks from Ubuntu). So, the common factor till now is that they (the 3 OS's on which the problem appears) are all Ubuntu based. So, I think it will be highly likely that others with Ubuntu fork distributions may also encounter the same problems, but not everyone may notice it or really use it, or think it is important enough, or make notice of it; whatever. I did, because I need it, but that may very well not be the case with others (I would not have mentioned it if 3.2 would be sufficient to me), so the urgency may vary, or the felt need to mention it. At least I have proven now that it is the case for more (3; Ubuntu Studio 18.04, KXStudio and AVLinux) Ubuntu based systems on different machines, with different sound settings and sound cards (my PC has a firewire soundcard and my laptop I had on a USB soundcard and then on the internal soundcard) and with different operating systems (the common factor however is; they all are Ubuntu based). Quote: "or we'd have heard at least one other report beyond this thread - indeed we'd have heard hundreds" is, how reasonable it may sound, yet an assumption. Many people may have large problems with some companies but may never mention it for many different reasons. Not everyone makes note of it (it depends on their interest) or if they want to go there or not. All kind of reasons are possible (or they simply won't notice the delay by not doing what I did). It is not an argument I find very convincing at all, with all respect. The only thing that matters, basically, is that it can be repeated, reproduced on other operating systems, with other sound settings (it does), preferably by more people (but the latter is not even absolutely needed). Reproducibility is the key. If so, it proves it does not depend on what I have on my PC or my sound settings there. It does not depend on that. So, the problem is probably wider and more substantially present (on other Linux-OS as wel; Ubuntu based). So, maybe I should install Windows again, one day, or buy a Mac, or use an non-Debian fork/distribution of Linux or wait for the developers of Ubuntu to upgrade what is needed. It is as it is. I have to learn to live with it.

Thanks. I might try that (Arch Linux). Have you tried it with MS 3.6? I recall I have installed ArchLinux in the past already once, but I may give it another shot now (but you saying it regularly breaks down is enough not to install it on a machine; just a live USB). I'm about to download Fedora and try that as well in a live environment, from USB as well (with the possibility to download and use the AppImage 3.6.0 of MS from there).

I don't understand it either. Maybe, even though it is an AppImage it yet needs some missing dependencies for it to be able to run? Although I also understand that's why an AppImage is used in the first place. So, I don't know; I'm not a developer (it was mentioned to me above). I'm just trying to figure out what works for me with the MS 3.6.0 App Image and can only speak for myself. The only thing I notice is that 3.2 works fine, but the latest AppImage 3.6 obviously does not, on 3 tested different OS (all Ubuntu based) and 3 different sound systems. Others can only speak for themselves when they test and try it and/or mention it; if they happen to test the same things and indeed mention it. You can repeat it a thousand times, but it does not make it more convincing to me. What matters is: has it been tested by anyone else of those thousands of users and has it been confirmed to work; not be an issue? Or is it supposedly working, because no one has mentioned this yet (except me; and I may represent thousands and thousands of people who may have the same issue; but don't realize it yet or whatever). If this has been tested to work, on what systems, and on what systems is it an issue? In the mean time I'll keep looking and trying what works for me.

Although I can imagine that the AppImage can largely, but not entirely work on its own and for that (the external connections) it may still require certain things who may, or may not, be available to the extend what the AppImage needs it to function well/best. But again, I'm not a developer.

@larshenrikoern. On my main machine, my PC, I have MS 3.2 installed from the repository (I added the PPA of mirabilos). That works perfectly fine. No problems whatsoever. Only problem is with the AppImage. It does not make a difference what I sound settings I use; they all give the same problems. Normally I use everything through Jack with all the bridges on and working. I don't switch. I use Jack settings in I/O MS as well and have always all the bridges running, including the PulseAudio bridge.
So, what you describe, I don't have at all. Even if I use Pulseaudio in MS (with bridges on) or Alsa, ar Jack (all with the bridges on), it all works; I have good sound with that, but I do have the same slowness problems with only the AppImage of MS 3.6.0. Then I just downloaded and ran a fresh install from a USB stick and tried an other fresh install (this time on my laptop). Both the same problems with the Appimage 3.6.0; sound system again not an issue at all. This becomes a repeating session. I'll keep trying and let you know the outcome. I have to try to figure this out myself now, I think. Thank you all again.

Ok. I figured that the Xubuntu version on my laptop had probably not been updated for a while (I have not used my laptop for a while). I thought it would/should make no difference, but I just decided to do it anyway. And guess what: It made all the difference. I just did sudo apt-get update and then sudo apt-get ugrade and then all of a sudden, after that, the AppImage MS 3.6.0 works like a charm on my laptop now. All delay problems are instantly gone on that machine. I believe those were Xubuntu updates from, basically Ubuntu 20.04. So, that works and it has to do with updates, so maybe dependencies is some form. I at least have it working on one system now, my laptop. That was unexpectedly simple. So it may indeed have to do with software or dependencies in the updates/latest versions. Peculiar. That is quite dependent I would say (on the latest updates). I updated (not upgraded) with the latest Ubuntu 20.04 updates (Xubuntu is a light weight for of Ubuntu). So, clearly, some dependencies from the updates of 20.04 are needed or at least make it work. It had version 20.04 of Xubuntu already, and so, for some reason, it clearly needed the latest updates.

So, this is hopeful (that it works on my laptop with an updated Xubuntu 20.04). I think I'll run the risk of messing the system on my PC now and try an upgrade to Ubuntu Studio 20.04 (again with KXStudio on top) on my PC. I hope it won't break my studio system (it did just that before; maybe KXStudio wasn't really ready then yet). I'll make a backup and try a fresh install. The website of KXStudio now says: The KXStudio repositories support all Debian versions since 10 (Buster) and Ubuntu 18.04 (Bionic) or above including Ubuntu 20.04. I'll make the result known here as well. I hope it works.

That was on my laptop running Xubuntu 20.04. I'm trying to get it working on my PC now as. I upgraded Ubuntu Studio 18.04 from within the OS to Ubuntu Studio 20.04. No success. Same problem; even worse. Trying to open the AppImage stalled everything. I'm trying a freshly new install now. I have no idea how to find out what did it with Xubuntu on my laptop. I'll keep you informed about (hopefully) further progress.

Thank you for your extensive answer and tips. I just did a freshly Ubuntu Studio 20.04 install. Even buggier. It stalls the system when even trying to run the AppImage. Next I'll try an upgrade to the latest, if that does not work. I'll go back to Ubuntu 18.04 or Xubuntu on my PC as well. Have to see how it all works out. Thanks again. And all the hard work you developers do.

Thanks. I tried that already (sudo apt-get purge pulseaudio), but in this case, completely removing pulseaudio did not make any difference (here it isn't the Pulseaudio system, but something else; I know for a very long time, for many years now, what problems Pulseaudio can cause). I need Pulseaudio on my PC, because I need to be able to hear YT musicvideos. UPDATE: I first did a freshly install of Ubuntu Studio 20.04 on my PC and tried to run the AppImage 3.6.0 of MS. No success; even bigger problems with a completely stall of the whole OS system (stalling everything and not responding; only a hard reboot, holding the on/off button on the PC, could bring me back). Then I tried to get KXStudio working on top of the OS, but that did not work as well. I figured, because the Xubuntu distribution worked on my laptop (including the AppImage after running all the updates; have an updated system), I then installed Xubuntu 20.04 on my PC as well. And guess what: it worked. Also my sound system/studio also seems to be working now, but I have not fully been able to test that, but everything looks good. Back to Qjackctl and that works also; Jack works fine (no more Cadence for now). I have not installed KXStudio on top of this Xubuntu install, because that ruined Ubuntu Studio, so I thought that to be too risky and it is not needed here, because in Xubuntu everything works.

So, it works. I'll keep that for now. I know that Xubuntu had a recent action with a lot of testing and maybe that is the reason why it works so well right now (in comparison to the other Ubuntu 'forks'). I have the AppImage working now, after a lot of trouble and let's hope that the rest will be working as well. Almost impossible for me to say what caused this, except it seems that an update on Xubuntu made it somehow work (however not on Ubuntu Studio; while both are based on Ubuntu 20.04).

@Jojo-Schmiz and mirabilos.
I went back from Ubuntu 20.04 to my old and trusted Ubuntu 18.04. See below (scroll down) for an installation instruction .

Thank you also for everything you do. I hope it will. I wish everyone who works on this it all the best.

It (Ubuntu 18.04 + KXStudio on top) may sound as a 'temporary hack,' but to me it is 'proven stable' and long lasting and far better working than any (stand alone) Ubuntu distribution I have tried and I have used this for many years. It provides a completely working system in Cadence for any sound card and it works flawlessly and everything connects perfectly well. This is not the case at all with all later versions of Ubuntu (and other distributions moving away from it). They mostly and exclusively work with the Alsa driver assuming a USB sound card (I doubt if thunderbolt will work at all, but I haven't tried that). Also Jack works best with this setup I have (in all possible setups; I also have a USB sound card with my laptop (Focusrite Scarlett 2i2), and I have used the same system on there as well (I temporarily switched to Xubunte, but now I installed it back to Ubuntu 18.04 with KXStudio on top as well); without all the 'bells and whistles'; all the studio software). So, I seriously don't understand why Ubuntu is not looking into this more. They should. They should return to having Jack as a solid and stable base and connect everything to that, by smoothly working bridges. Now it all seems like a loosely (dis)connected and unstable system which often breaks down (also USB based). The people at KXStudio have gone to great lengths to make it working and they apparently know what they are doing. So, the people at Ubuntu should learn from that and incorporate that, I think.

I would say, give it (Ubuntu Studio 18.04 with KXStudio on top) a try if you have a Firewire sound card
Works best (all later/newer Ubuntu versions is a 'no go').

(The M-audio profire 610 soud card works great on Ubuntu 18.04, together with the above OS-hack (first start 'Ffado, then in Cadence select 'firewire' and the right settings; see above). Windows 10 is no option, because the driver for the sound card is not being updated by the factory/company. I tried it with Windows 10 and I had many unsolvable drop-outs of the soundcard; unworkable. Besides that, using Jack in Linux is a great advantage, because one can connect any software package to it and it won't hijack the system; in Windows and Macintosh the sound is exclusively hijacked by the opened software package. With Linux I can play any sound from any package, even through each other and they all work and can be connected. I tried Jack on Windows; it hardly work; not as it should, not as with Linux! Of course the Focusrite Scarlett 2i2 USB soundcard works with any Ubuntu version, 'out of the box').

Ok, thanks, but have you seen what the site of KXStudio says, quote: "All Debian and Ubuntu users can enable our repositories...". See middle of the page (Deban/Ubuntu): https://kx.studio/Repositories

If you do it like I did (and I put the description in the link above) it won't create bugs and instability. After everything works I turned off the updates (except security updates) then it keeps on working just fine. It is very stable (Ubuntu 18.04 + KXStudio on top). But, like I said, other distributions are not. This is the only one that works with me (I believe 16.04 also worked, but certainly not the younger versions).

@larshenrikoern. "if you never change anything or get new hardware you will not have new bugs. But anyone who has other hardware and needs cant use it." I'm trying to say that the system I have works without problems with more hardware (Firewire/USB) and has no limitations (while the newer versions have). It is not true that I don't buy new hardware (Like I said, i did buy and also use a USB sound card (Focusrite Scarlet 2i2) ), but many have or even buy (new) Firewire soundcards today and that still also should work. It is not the normally a principle that older hardware should no longer work on Linux, rather the opposite; the other way around (Linux is supposed to work fine on older hardware, where Windows and/or Mac. won't work any longer). So, they should not simply say 'we don't support it any longe, just buy new'. That is the wrong way, and not typicol Linux, and also many professionals still use Firewire and that is still the superior way over USB (even USB 3.0). So, if I would buy new, it would be Thunderbolt, but who guarantees me if that will work if this even does not work (Thunderbolt is the new Firewire). I want it to be tested and proven to work (so I read many reviews/forums about that, before I even buy).
Sorry, I don't understand the sentence: "If you compile your own kernel (I do among other things that) I can have firewire among other things with even the newest kernel." "But next time asking for help be please a bit more patient." I think my extensive testing and trying and reporting it here rather shows my patience than that the opposite would be true. Also, you saying: "I do not think anyone did figure out what the bugs were that caused the original problems" . You can only speak for yourself, not for anyone else. Thanks for your patience, if my response was too much for you or somehow annoyed you. Not intended at all. I highly appreciated your response... anyone's response and I read and thought about them carefully.

@mirabilos. Yes, that may be the right conclusion. Interesting, isn't it. Yeah, being wary is probably the right way to go with this. I have no experience with recompiling. No idea what you mean or how I should or if I should at all. I'm not a very technical user (no programmer or developer), just a user.

Ok, maybe I'll look into the advantages of compiling one's own version and if and why that would be useful (but I figure that is way above my expertise/knowledge level of Linux). I understood from the answers above at some point, that I basically was on my own and I had to find a solution myself (remember that the initial goal was to get MS3.6 working; and I needed that relatively fast). And then I decided to inform you all, and anyone else who it might help, further about the process of what I did and how I got it to work. As a sort of extra, as possibly helpful information to help anyone further or give clues to developers as well maybe, rather as a sign of taking everyone's help (above) seriously, and not at all to waste anyone's time.

Thanks for your extensive insightful explanation and as for me trying Debian; I did that more than a decade ago, when I ran my own web server (without GUI). I have everything working now (including MS3.6 as long as I don't try to activate the navigation view/panel) and as they say; 'don't change a winning team' (and by the way, I did try out AVLinux (as you may have read above), which is based on Debian; it used Qjackctl and I could not get my soundcard to work there with the firewire driver). So, I'll stick with this for now.

Here you can find my installation and configuration, based on Ubuntu Studio, with KXStudio on top. All is focussd on Audio, connected through and to Jack with firewire. (I have a home music studio with virtual pipe organ running on GrandOrgue and an M-Audio profire 610 external sound card, I extensively use Ardour, Audacity, Musescore and GrandOrgue; and they have to be able to work together).
See attached.

Now I yet have to figure out how to make an image or live distribution of my system, which I must be able to boot and install from that live version (iso on USB-stick), just as with any other distribution. I tried some solutions online, but for that I had to install things that gave unsolvable package conflicts. If I have that tested and working, I'll put it here for completion purpose (and to keep having a stable working sound system, which is very important to me).

By the way, the latest AppImage works fine now, with my latest install; see my post above of Feb 2, 2021 - 10:06. Except that 'the navigator' loads slow at initial load/use and then blocks MS; I have to wait until it appears; which lasts 10-30s or so). But, other then that, everything works great!
A big thank you for the developers (volunteers), who work so hard on this and keep doing so.
(OS: Ubuntu 18.04.5 LTS, Arch.: x86_64, MuseScore version (64-bit): 3.6.1.515740129, revision: d0fc8e9 )

Yes.