The performance of your Screens comes down to following:
The memory and power of the device running your Screen.
Higher quality, better equipped devices that have greater memory and faster processors will always run your apps more efficiently. There is a huge variety of device options, particularly with Android, and so whenever possible you should specify known, tested devices for your users to procure.
Total number of fields in a Screen
We don't have a hard upper limit on field numbers, but we recommend staying under 2,500 fields in a Form design.
How these fields are distributed across Form pages.
We recommend staying below 100 fields per page in your design, as each field in a page has a device rendering cost that impacts memory usage and performance.
A mix of field types in a Form page.
Certain field types have greater memory and performance impact than others. Image fields incur overhead due to the inline display of image snapshots and associated editing functions.
The total number of Data Sources involved, and the number of rows in these Data Sources.
We don't have an upper limit on how many Data Sources can be linked to a Screen design. Note that each additional Data Source that is loaded to your Screen will have a memory and performance impact. This impact increases with the number of rows and columns involved.
For example 50 Data Sources with an average of 100 rows each and will have lesser performance impact than 10 Data Sources with 50,000 rows each.
Using the guidelines above will help you to build a performant, stable app on our platform. You should always test your designs on the devices you expect your users to have. This way you can gauge the performance and make tweaks to your designs as needed. Whenever possible you should recommend specific, tested and trusted devices for your users to purchase.