Playing Power App Long Load Time

[quinncain]

My Power App I'm creating is taking a very long time to load when a user click play. I have screens with forms that load when a user selects an item from a gallery. These screens with edit forms all rely on the same gallery, but are navigated to depending on the contents of 2 columns from the selected row. I'm worried that on start this is loading information from the gallery into every edit screen causing a huge amount of slowdown. I was wondering if I could load certain edit forms contents only after the user navigates to the desired screen, or is there another way I could optimize this app to load faster other than by removing controls? I've drastically reduced the number of controls to the recommended amount and this slowdown is still occurring; I'm wondering if the issue could be the edit forms.

[RandyHayes]

@quinncain 

9 times out of 10, slowness has little to do with the controls and everything to do with your formulas.  

I would start with the monitor tool to monitor your app when you play it.  This will give you some guidance on where to start looking.

Things to look for:

- Are you utilizing the OnStart and what are you pulling in there?

- Are you directly connecting/referencing the datasource in galleries or other list-based controls and (more importantly) are you then referencing the controls with a .Selected property to fill forms or perform other actions/lookups based on those selections?

From the above two, neither is necessarily bad, but they need to be applied in such a way that performance is not impacted.

So, try to start with the Monitor tool first and see if you can gain any insight from that.

I hope this is helpful for you.

[quinncain]

OnStart Property - The only thing I'm utilizing the OnStart property for right now is navigating to the home screen. This only appears once within monitor and does not seem to be the issue. 

Functions - There appear to be a LOT of functions running at any given time within the app running. I'm getting around 3.5k function pings as soon as the app starts in monitor which can't be helping the launch time.

Datasource Refernces -The gallery controls directly reference the datasource, and the edit forms fill by having their items property set to Gallery.Selected. 

How would you recommend applying these aspects to improve load time? Is there a way to only have the functions of certain text fields execute when the user is currently on the screen where said textboxes are located? These functions primarily rely on information of the screen the user is currently using, but some use information from other screens. The functions only rely on columns from the same row; there are no lookups for these functions 

[quinncain]

Clarification about the last bit, the data used in the functions is pulled from the edit forms, which is pulled from the datasource. These functions are pulling the data from the loaded textboxes on the edit forms, indirectly from the datasource in a way.

[RandyHayes]

@quinncain 

The thing to keep in mind is that PowerApps is exactly like Excel in that it has to evaluate formulas all down the chain.  It is not like a development platform where things only happen when you code them to do so.

So normally, having a Gallery and then using the .Selected can be just fine.  But if you have many other dependent formulas that base their values off of the gallery, or the form or anything else that stems from the top (the gallery in this case), then those all need to evaluate.  Again, this is, in many cases, not an issue.  But if there is a lot, then it can bog down the app.

You can start by replacing all the .Selected references to a variable.  Changing the OnSelect of the Gallery to set a variable (i.e. Set(glbCurrentRecord, ThisItem) ) and then setting the Item property of the Form to glbCurrentRecord

This will cause the downstream formulas to only evaluate with data when something is actually selected.  Otherwise they will be working with blank data - which should not take any time.

Also, the default settings for the features in PowerApps are typically on the side of higher performance.  So, if you have changed any of those, then there is the potential that one of them is set wrong.

[quinncain]

On start nothing is selected, so these formulas are already being evaluated with blank data. I went through and changed my .selected statements to variables just to make sure nothing changed in monitor, and I'm getting the same information. Evaluating these blank entries is still taking a long time; its taking nearly 10 minutes for the app to launch. 

[quinncain]

This may only be a problem on first start I'm realizing, but I'm not sure why. I press play again after the first time I loaded it, and it was very fast, probably less than a second. I then relaunched edge and tried again and it also launched nearly instantly. Why is this happening? Is the app being cached to memory within edge on first start, so subsequent launches are faster?