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App Designer's editor is slow and gets stuck alot

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I started using app designer instead of GUIDE a week ago, and some things really annoy me about it, tho it is beautifull and has a lot to offer.
The first thing is that app designer lack a lot of components and features guide has, like coping figures and adding java components (and no way of inserting html in labels).
Is this going to change in the future, or is this intended?
The second more importent thing is that when my code has more than ~100 lines, app designer's editor turns out to be very slow, and now - when my 'app' has 1k lines of code, app designer is unbearable and when i write something i need to do it in an external editor then paste the code in - which ALSO takes forever.
Litterly, i press Enter and i have to wait 10 seconds for the editor to respond. Pasting takes ~20 second, and writing a full line of code will take me about 10 minutes. No joking.
My task manager pointed out that after i do anything (and the editor is processing), matlab takes ~30% of my CPU and 200MB RAM.
While the editor is processing, it's whole gui is stuck also, meaning I can't close app designer, I can't save my work, I can't do anything.
Those are 'bench' resaults:
What should I do? How can I make app designer faster? And is app designer a beta or something that's gonna have more features in the future?

Accepted Answer

Etienne on 20 May 2016
FYIW, I was on the line with the helpful people at technical support this morning. The code editor slowdown is a known issue. Over 800 lines of code with the "enable coding alerts" or over 1500 lines without the coding alerts is known to cause a slowdown. Here's what they explained:
  1. 2016b will greatly increase the performance for larger apps. I've been told that the performance up to 5000 lines of codes will be improved. 2016b Pre-release is coming soon.
  2. 2016 or 2017a will enable more components, including tables, which will (for me at least) greatly reduce the number of components, which will reduce the number of command lines, also improving performance.
  3. Coding app methods can be moved to helper classes, which can be coded in the normal matlab editor, which also reduces the number of app designer lines.
Hope this helps

More Answers (20)

afalv on 28 Nov 2017
Non-sense post, but just to keep this thread alive...
The App designer is SLOW!
I have a hell of a machine that can fly to the moon but I cannot write any significant amount of code in the app designer. Now I have 1.5k lines and it feels like I work through remote desktop from Mars.
This is the last time I started a project in the app designer. I just don't want to outsource every little peice of code into a separate function file just because the editor is unable to handle ...code.
I bet the only problem is the poor performance at syntax-highlighting. Can't you just use the Eclipse-Library or something else that works fine for 100k+ lines of code?

Michael Zimmermann
Michael Zimmermann on 17 Mar 2021
Edited: Michael Zimmermann on 17 Mar 2021
This is my first post and I just came here to leave my two cents on AppDesigner after fighting/using it for a couple of weeks. I had used the usual figures earlier (which I personally always prefer) and always avoided GUIDE due to the code overhead it produced, but at the moment I have no choice.
Background: I have seen quite some code in my career (10+ years of C/Python/Matlab experience) but am not a full-time developer. Now, I took over a 3000+ lines application which a student of mine which has built using appDesigner. I'm using 2020a as of today. For algorithmic reasons, It's crashing in unpredictable places now and then, so I would like to look at class/app variables as much as possible in these cases.
Overall problems I see with AppDesigner, leading to frustration at times:
1.) As people seem to have noticed, the editor is slow.
2.) The packed *.mlapp is useless for version control. Or did I miss something here?
3.) Seeing internal variables without setting breakpoints is only possible with workarounds (app->assignin->base workspace)
4.) Im some cases, Matlab UI and AppDesignerUI freeze, and none of the closeWindow buttons work. Only chance: Taskmanager -> Roundhouse Kick of Mathworks Products. Like half a dozen times a day...
5.) Huge screen space need. If I want to look at App/Matlab Main UI & the actuall application, it needs 3 screens.
6.) The Layout you have set up in the Design View and the actual app do not properly match. Especially when the App is built quite huge and AppDesigner tries to rearrange things when the App Window is scaled.
7.) Funny one: If you rescale the UI in AppDesigner (Mouswheel + Ctrl), the mouse and box selection do not match any longer at times. See below. I moved mouse like A, but the box select opened up B. Now try to select elements in Design View with this!
Maybe someone from @MathWorks Support Team can put point some AppDesigner devs to this post.
Have a nice day!
PS: If I get asked if I'd recommend using AppDesigner, I tend to "No" at the moment.
  1 Comment
Mark Magdaleno
Mark Magdaleno on 17 Mar 2021
Mathworks can we acknowledge the elephant in the room here? I have completely given up on App Designer for all the many reasons I and others have mentioned. Even with all the bandaids mentioned, using App Designer is still like running through wet concrete compared to GUIDE or programmatically create controls that are not AppDesigner based (there is a difference). Does anyone at Mathworks notice this? Again this will only get better and instill confidence in your customers if this is acknowledged and acted upon. I have seen this languish for decades now with maybe a few negligible improvments that are just trinkets really. Like Kenny Rogers says "You gotta know when to hold them, know when to fold them".

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Melissa Williams
Melissa Williams on 20 Mar 2020
MATLAB R2020a, available now, has some great performance improvements to the App Designer coding experience. Check them out in the release notes. Select product->MATLAB and scroll down to the performance section and expand the App Designer Code View section.
Joseph Pittman
Joseph Pittman on 13 May 2020
Edited: Joseph Pittman on 13 May 2020
On Arch it's completely unusable. If the app designer editor was written in app designer, I hope guide remains supported. I have an 4 core i7 @4.2 ghz. It runs on one core with a full second delay between key press and text appearing.
Kevin S
Kevin S on 29 Oct 2021
My goodness... I don't even want to know what the experience was like before 2020a... I'm using 2020b and still pulling my hair out over this. I love the App Designer editor, but the performance is just abysmal. Please, scrap the "UI" stuff and focus on improving what already works; give us the performance of GUIDE with the simplicity of the of App Designer editor.

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Hendrik B.
Hendrik B. on 28 Apr 2016
Edited: Hendrik B. on 28 Apr 2016
I have exactly the same problem. The bigger the program gets, the slower it is. At the moment, it takes almost 10 seconds after I change something in the code.
Hendrik B.
Hendrik B. on 29 Apr 2016
I already tried that. It is still as slow as it was before. At the moment I have 899 lines of Code and about 63 design elements (spread over 4 Tabs).
Mark Magdaleno
Mark Magdaleno on 13 Jan 2021
I too have also disabled coding and still very slow.
Mathworks Serious question; Do you not see what all these App designer users experience and report? In order for this to be solved there has to be a realization of the problem. Mathworks is this a problem?

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Vishal Sharma
Vishal Sharma on 19 Feb 2020
Appdesigner is definitely i wont suggest anyone. I have been working on it and its a nightmare. It's easy to use but so slow, that i decided to get back to usual m-scripting based GUI. Apart from being slow, there are so many limitations with the Appdesigner, which could have been handled otherwise.
has anyone faced problem while opening the app in appdesigner? it never opens for the first time.
  1 Comment
Punit on 7 Apr 2020
I have experienced the same. But disconnecting form the internet and restarting the computer speeds up the process. Also no browsers should be open to speed up the appdesigner

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Murat Panayirci
Murat Panayirci on 10 Jul 2020
I came across this post while I was having the same issue: app designer becoming unbearable over time! I started with such enthusiasm to use the app designer after seeing all the feautures and ease of developing a GUI. However over time, as you invest more and more in it, the editor becomes unworkable as many people have pointed out here. And the worst is, by the time you realize this, you are already here reading this post and have 1000s line of code.
Before anyone mentions the improvements in the lates version, I am using the latest version of matlab ( ' (R2020a) Update 3') on a pretty new powerful laptop + Enable app coding alerts turned off..still no good.
Another annoying thing is that I have contacted support and they wanted me to send them all kinds of information, which I spent time on. I would much rather that they told me "look we know about this issue and we are working on it!". That would have save me time as well.

J. Webster
J. Webster on 14 Apr 2016
I recently started using App Designer myself.
This is the first time it's been included with a normal installation, so yes, it's still a bit buggy. I consider it a beta release, whether mathworks does or not. I've noticed the unresponsiveness as well, though sometimes restarting matlab will clear it up a bit.
You probably wouldn't want to use it for any "mission critical" projects yet.
  1 Comment
Tor Hadas
Tor Hadas on 14 Apr 2016
I use it for testing currently. In my pc the app designer is unresponsive everytime I input some code which makes writing impossible. Restarting matlab won't help

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Chris Portal
Chris Portal on 15 Apr 2016
Tor, can you go to Code View and try turning off the "Enable app coding alerts" checkbox? See if that helps address the performance issue you are experiencing. And yes, App Designer is under active development so there are many more features in the works.
Tor Hadas
Tor Hadas on 20 Apr 2016
I tried that already and to no good.
My current solution is to call functions from a .m file containing all the real code, thus not having to deal with app designer's code editor
Chris Portal
Chris Portal on 21 Apr 2016
Hi Tor,
This is disappointing to hear. I would've expected turning off the alerts would've made a significant improvement. We'd like to investigate this further to better understand what is impacting your app.
If you don't mind sharing your app, could you contact me through my profile so we can arrange a way of getting a copy to troubleshoot and add to our qualification process?
Thanks for all the feedback!

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Chris Portal
Chris Portal on 5 Aug 2016
FYI, an external bug report has been posted on the MathWorks web site with some more information on this:

timo on 27 Aug 2016
On a core i7 laptop with 16 GB of ram around 1200 lines it takes 1 second delay to type ...WTF

Chris Portal
Chris Portal on 23 Sep 2016
For those who may not be watching the external bug report for this, R2016b addresses most of the issues reported on this thread. I encourage you to try out the R2016b version of App Designer when you're ready to upgrade.
Moses on 26 Sep 2016
Yep, I just tried out the App Designer editor for R2016b and it seems to work fine now!
Chris Portal
Chris Portal on 8 Oct 2016
Great to hear Moses! Thanks for the confirmation.

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Valber Cavalcanti
Valber Cavalcanti on 31 Oct 2017
Edited: Valber Cavalcanti on 31 Oct 2017
To use the Matlab AppDesign is getting terrible experiences for me. After all my programming and designs, the AppDesign re-copy several components that I already delected. Is always slow, and for many times noting works, definitly. I lost hours and days with this AppDesign. It is not fair.

Christopher Braunholz
Christopher Braunholz on 13 Aug 2018
I got to the point of an unasable App editor (R2017b, Enable app coding alerts is off) now as well. 3500 lines of code seem to be too much... Matlab, please catch up on this!

Andrea Carignano
Andrea Carignano on 27 Dec 2018
Edited: Andrea Carignano on 27 Dec 2018
I updated my Matlab from 2017b to 2018b and the performances are significantly worsened.
Editor become unresponsive more frequently and I can no longer copy and paste code because nothing happens when I do this. My app has 7000 lines of code and nothing changes if I enable or disable app coding alerts.
Also debagging has a lot of problems. When I stop at a break-point the command-line takes 4-5 seconds to run a line of code, and then I am not able to continue or quit debugging or save the code.
It is impossible to work this way. I strongly advise to avoid app designer for big projects.

scott nolan
scott nolan on 26 Mar 2019
I have been having way too much trouble with this very buggy API/Compiler.
It is slow - very difficult to work with even if you are an experienced programmer ( 35+ yrs here)
it cannot work with activex objects - so you cannot write out your results
so you cannot share your results ( unless you do screen grabs of charts, etc)
and Matlab help desk will not answer questions regarding the API roadmapp - so you cannot determine if it is a waste of time until you invest a lot of wasted time and eventually find all the dead ends.
using 2018b

Etienne on 13 May 2016
Edited: Etienne on 13 May 2016
Adding my voice to this problem since even tech support seems to be unaware of the problem.
I have the same problems, I've given up on copy-pasting entirely. Restarting Matlab sometimes helps.
I have no clue why the editor has to be this buggy and laggy - and why can't we just edit the code with the regular editor?
Chris Portal
Chris Portal on 5 Aug 2016
A word of caution for anyone that tries this undocumented/unsupported poking into their MLAPP file. Taking this approach will almost certainly guarantee your app to not load in one of the subsequent releases. Just something to consider in your off-roading expedition!

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Bradley Stiritz
Bradley Stiritz on 4 Nov 2019
Edited: Bradley Stiritz on 20 Mar 2020
EDIT 3/20/20 : Happy to report that we're not having any more problems in AppDesigner R2019b. One additional tip that has worked for us, and may help others: use a strict Model-View-Controller paradigm--
  • separate classdef AppModel, with all back-end implementation code
  • minimal user code in the AppBase-derived class. Callbacks simply update properties and call corresponding AppModel methods.
EDIT 11/13/19 : we found that stability is much better in Windows, vs. Linux. We're now only developing Apps in Windows 10, it's a much improved experience!
ORIGINAL POST: A sad update on this thread discussion-- A friend and I are using R2019b. Last week, we started prototyping a very simply design layout. AppDesigner has been slow and buggy. Sometimes it hangs, and we have to restart the Designer after the project is saved or the app is launched.
As a long-time, devoted Matlab user, it's painful to see that AppDesigner stability and usability still hasn't been achieved yet.

Punit on 7 Apr 2020
I have experienced the same. But disconnecting form the internet and restarting the computer speeds up the process. Also no browsers should be open to speed up the appdesigner

Muhammad Zeeshan Ahmed Khan
My version 2021b not even gets it start only a white screen

Ivo Lipkowitsch
Ivo Lipkowitsch on 8 Dec 2022
I'm using 2022b and for a while AppDesigner worked fine. The Editor doesn't freeze liek previously described.
BUT. After pushing buttons in my GUI after some time the APP freezes entirely and I can only kill it via taskmanager.
So far nothing helped.
  1 Comment
HaJo on 28 Mar 2023
Same here, since version 22b the crashes/freezes have become more frequent. Seems, that we have to wait for next version?

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