Hi all,

I just created a dropdown function on mobile, but unfortunately the dropdown function is not performing really quickly. I kindly want to ask some tips that maybe could cause the delay in performance. Beneath one can find the details of the process:

Within the app one could select a category. These are tile with icons. If one select the icon, the icon will be highlighted. Meanwhile the dropdown can be used to select a subcategory. We are talking about 6 categories with each consisting of 1 to 3 subcategories. So we are not talking about a large table of records. 

Below you can see the flow when a category is selected. First the assign is assigning a variable with the selected category. The switch is checking which category is selected and the assign is giving that concerning category the highlighted image with a Boolean. After that the data will be refreshed for the drowdown that then will show only the belonging subcategories. 

In my opinion this flow is not really special, so I am really curious how I could improve the performance. Because now it really cost around 2 to 4 seconds until my dropdown is showing the belonging subcategories. 

Ps. the internet connection is good and could not be the problem. 

Thanks in advance! 


Hi Martijn,

Although as you state there is not much data, as long as every time refresh the data which is stored on the server you have a round trip to the server. If you want to improve performance create local storage entity version of your entiteits and synchronize the server data to local storage, you can use standard outsystems scafolding to generate simple sync pattern as you state data is limited in size and i think only use to read and don't need to be updated.

This will improve your performance. As all processing takes place only on device and no connection to server needed.




Hi Daniël,

Thanks a lot for your reply! It all sounds pretty obvious that this could help! 

I will work on it.


Hi guys,

Can anyone explain me how selectedindex event will work for combo box.

See my requirement is based on  selected value i need to enable another combo box list.

Can you give me an example.



Hi Martijn,

Always avoid using calls to the server in components like DropDown, Radion Button or CheckBox. You can create a variable of the type of your query and do the operations on this variable, this will greatly improve your performance. And the data synchronization you can do the way the Daniël commented.

Good job ;)