Gallery scrolling performance issues

[pmcgurn01]

I'm hoping there's some kind of planned performance improvement work on the gallery control, but posting this, in case there isn't.

At present, the gallery control is incredibly clunky/laggy when scrolling any faster than what I'd consider to be "unreasonablly slow".  The behavior is 

1. I scroll
2. The rows move up
3. There is a huge empty whitespace for about 1-2 seconds
4. The white space fills up as the elements render
5. Repeat process

I will note:

• It doesn't matter if I bind the gallery to a local collection or directly to the data source.   Since my data source (Azure SQL) is too large to be cached to a collection, I'm limited to direct binding anyways.
• It's reproducible in web player (Chrome browser) and mobile (iPad app)
• I am using ThisItem to bind all data to controls in the gallery.  At this point, I have 8 controls total in the template row, which are a mix of images (2 icons) and labels (6 of those).
• It seems to be completely unrelated to latency in the network.  I can verify this by watching the troubleshooting console, and the lag isn't tied to any network calls, though I do see those happen at each 100 rows of data or so.
• I can reproduce this on other data sources that I am caching to a local collection on app OnStart, where I see this empty whitespace when I scroll fast enough to where the gallery would need to render more than ~5 rows at a time.  In that case, the datasource is cached to a local collection, and that gallery only has 5 labels in the template row.

I'm attaching a video of this behavior.  While the lag you see might be "acceptable", it's not a great user experience on any platform. I understand that the gallery is probably working as designed for keeping resource utilization low on mobile devices, however, since this can be reproduce on mobile, too, I'm asking that Microsoft improve this. 

[zaina]

whenever i scroll down it goes up on the top. is there any permanent fix for this ?

[zaina]

Yes we are also facing this issue. and problem is that if we go back to old version it is only temporarily when we open power apps studio it goes back to new version with scrolling issue. and we can not send new deployment to clients due this scrolling issue. 

Other things with same new versions my half team is facing this issue and half team is not facing issue, all of us are on same new version. and we have not heard anything from our clients means they are good i think but i have a fear if we send ne deployment to clients they will start facing this issue.

so any permanent solution for this please? will be very appreciated.

[oldman]

It is possible to increase the amount of records that stay loaded in a gallery. This decreases loading times a little but helps when scrolling up and down as nothing visual is being updated by the renderer.

1. Create a (vertical) container with fixed height of the size you want your gallery to be on the screen.
2. Insert a Gallery into the container and choose a ridiculous large height. All the records/elements within this height are being generated and can be displayed almost instantly without much loading.

My approach is to paginate the gallery and display a limited amount of items per page ( e.g. FirstN( source, 100)). This allows the user to scroll through a set amount of items with a fast responding gallery.

[OscarSotoCL]

Great Idea, i had the same problem with a Gallery. Copied a Canvas and datacard from a Scrollable Screen to my original screen and insert de gallery onto the datacard. No more load on scroll problem.  Thanks for your idea

[WheresWally]

Hi, 

If you have the time, could you describe this a little more please? 

The part I don't understand is the copying of a Canvas. Not sure what a Canvas is exactly - note I haven't used older versions of powerapps so perhaps something has changed. Also datacards only seem to be available inside forms as a control. 

I have 800 rows to scroll through with at least 20 columns of which about half will have editable controls. The scrolling is lagging very early on in the build with far less controls than that and with all the filtering and onchange events removed. I am running out of things to test and am not sure if I'll ever make an app that users will accept the scroll speed of. I scroll down with any kind of speed and the loading wheel appears for a good 4 seconds. 

Thanks

[cwebb365]

There isn't really a good option right now to handle that amount of data and scrolling that's built into the product. Your best bet is custom PCF grid control (which I never got around to doing a video of, sorry all lifes been hectic...) or using model driven apps which requires premium license and you may not fully like the grid UI options there as it uses paging at 50 or 100 records but the UI is nice and very filterable for working with large data sets and you can use editable grids as well with sub grid controls. 

The pcf method is very performant but mine is read only, haven't looked into inline editing ones which are possible but would require much more custom coding. 

[OscarSotoCL]

The Canvas and Datacard are objects that appear when yoy create Scrollable Screen.  You could copy these objects to any other other screen.  The Canvas control the visible portion of the object, and the datacard could be longer, and is scrollable. The you could insert a Gallery into the DataCard Section.  If the gallery it's too large, it will take longer to upload data, but in that way you could avoid the constant refreshing of the gallery.  It's maybe not the best way to work with gallerys, but it works.

Hope that helps

[WheresWally]

Oh thanks, I'd never heard of a scrollable screen before, so that's helped immensely. It immediately solved the scrolling issues which is fantastic. But in a classic 'good news bad news' way it's slowed all interactions with the controls within the gallery and the loading time of the data is now about 5 minutes (for only 800 rows!) so I'm going to try trim fat in other areas, maybe some of the containers I was using to achieve horizontal/vertical scrolling before can go. Thanks again. 

Ps. I'm loading a month of data at a time (~800) rows per month. I wouldn't mind so much if just loading the month took a while, but I'm also saving modified rows to a collection, patching that to a dataverse table when the user clicks a save button and then bringing them back into the gallery collection - which refreshes the gallery and takes the ~5 mins all over again. I might skip bringing them back in and just patch the changes directly to the collection when I patch them to the dataverse table. It was serving as a nice check that the changes made it in full though. 

[WheresWally]

Thanks @cwebb365. I had looked at model driven but couldn't work out how to do what I'm doing in canvas, namely:

1. dataflow from SQL server on prem into a dataverse table

2. Query another SQL view in the powerapp directly - with user selected date filter variables.  (collection1)

3. Query the dataverse table from step 1 with the same date range. (collection2)

4. Use addcolumns to left join collection1 onto collection2. (collection3)

5. Use collection3 as the Item source for the gallery, filter options and sorting on every column, data entry on half of them. ~800 rows of basically an excel document type arrangement for users to classify individually and batch classify rows (I have a neat batch panel that pops out in a container on the left). 

I will google editable pcf. Unfortunately I'm building in a bit of a rush so starting fresh is tricky. 

Thanks for your advice!

[cwebb365]

Pull the whole Filter of the Dataverse data into a collection and use that collection in your gallery. Then patch the collection with edits, then save button patches collection to dataverse table, it'll handle the row updates itself and should be more efficient, assuming the datasource can be pulled to a collection and isn't to complex.