Data viewer list causes app to slow down

Has anyone noticed that when you have lets say 100 rows in your data viewer list the screen slows down tremendously?

when my screen starts, a web api’s json response populates a local database in my app.

my data viewer list is connected to that local database, and when there are 10 rows the screen works fine, but when i add 20 rows or more there is a noticable slowness in screen components such as if i want to press a button it takes a second instead of instantly.

and when there is 100+, then a button takes 5+ seconds to execute (p.s. the button is outside of the data viewer list).

has anyone found a solution to this? and am i the only one who has this issue?


1 Like

Without knowing more, I’m going to assume the API has nothing to do with this and the button’s functionality has nothing to do with this.

So you’re saying that a DVL with 20 or more rows causes buttons on the same screen to respond slowly regardless of the code used for those buttons? How many columns does your data source have? And how many columns are you displaying at once in each DVL row?

Can you provide a link to a project that demonstrates this behavior?

You might be interested in this recent topic:


I just tested a DVL connected to local table with 9 columns and 50 rows and there was no delay.

The delay in my code was caused by deleting all rows in the local table and repopulating it again but that took around 5 - 7 seconds only.

My project is big so i’ll try to make a simplified project which focuses on the issue and i’ll send the link soon. thank you for taking the time to look into this

1 Like

@tatiang @muneer

I’m very sorry about the late reply. I’ve just started a new job and had to give it some focus.

please visit this project and you’ll see my problem. if you wait for enough data viewer list items to load (50+), you’ll notice that if you attempt to type in the text input and expect the “send” button to be enabled as per the code, it takes a few seconds to do so.

also if you attempt to press the “Send” button to show the alert, it sometimes happens instantaneously and sometimes takes seconds.

This is exactly my problem. and my app depends on data viewer lists. I think it’s also noted that my app uses firebase for triggers and listeners, but it doesn’t seem to be the cause of slowing down the app here.

In my original app, I get JSON data from MongoDB which is fast, but when enough data is populated, the screen itself slows down including all components within.

in some screens, even the back button takes 4-5 seconds to work.

I would appreciate your help since I’m stuck at this stage.

Thanks for your time

1 Like

I forgot to point out that if you attempt to input text while the list is still under 10 or so rows, you’ll see that the performance is fine, and it only deteriorates with more rows until it becomes more and more noticeable after 30 to 40 rows.

1 Like

I tested your app and can confirm the slowness.

I changed the custom data viewer layout with a layout I have and I can see significant improvement if the response time.

See this

@muneer it looks great on your side. can you please explain to me what made this difference or what i’m doing wrong that’s causing the app to slow down?

Appreciate your kind feedback.

1 Like

I believe that the issue is the way the custom layout is done. I believe the way you go about it is to first use one of the pre-loaded layouts and run it and time it.
The next step is to use your layout and again time it.

If there is an apparent time difference then it must be the custom layout.

And by the way,
Congratulations on the new job.

@muneer thanks alot i appreciate it

I’ll try to test this and let you know if it turns out to be the reason for my app slowing down.

1 Like

@muneer I’ve tried to use the default data viewer lists but i noticed the same performance.

then i tried to do a responsive web test instead of using my phone and i noticed it was fast the same way you showed me. can you try to test your custom layout on a phone instead of web and inform me if it’s still fast?

I have a feeling that the problem is the phone RAM cannot handle data viewer lists when they’re over 20, even though i have a relatively good phone (Note 8).

Kindly advise.

1 Like


This is the same project from my phone

This topic was automatically closed 90 days after the last reply. New replies are no longer allowed.