Format rule may be expensive and slow the user experience of your app

[Dev_TI]

Hi,
we are having a performance issue with our apps, the app shows the following alert:
“The condition of format rule ‘Médicos’ may be expensive and slow the user experience of your app”
We have identified that the alert is because of this formula:
OR(LOOKUP([_THISROW].[Médico],Médicos,Médico,Classificação) = “1”, LOOKUP([_THISROW].[Médico],Médicos,Médico,Classificação) = “2”)
but we do not identify what is causing the problem in this formula, does anyone have any suggestions for improvement in this formula?

[LeventK]

@Dev_TI
Are you looking up the value of a column in another table rather than the table that you are applying the formatting rule?
I mean is “Médicos” table the same table that this rule is applied?

[Dev_TI]

Yes, the table “Médicos” is in the same table of the rule.
This problem has started recently and this formatting rule has always existed in our app.

[Steve]

Format rules are applied in real time to the rows included in the on-screen view. If your tables are large, the expressions used by your filter rules could take a lot of time to compute and slow the app. For this reason, it’s a good idea to keep format rule expressions simple and (as @LeventK is getting at) to avoid filter rule expressions that use other tables.

[dbaum]

This would be helpful to explain in the Format Rules: The Essentials or another applicable article. There are several threads in the forum about the "Expensive expressions in a formatting rule can significant slow down the app UX" warning, and this is the last reply of the last thread that I found and read through.

In my case, the warning appears on a format rule that applies to a column that appears only in infrequently used views, which are based on a table with only dozens of rows. So, your explanation is helpful in evaluating that the warning's described impact seems likely to be minimal in my app.

[lizlynch]

Thank you for this valuable input! I've added a note to the Format Rules: The Essentials section, as suggested. I plan to revisit the app performance information in general in our docs in the not-to-distant future to ensure the information is surfaced in the relevant articles.