Performance issues with Mac Catalyst

[akgulebubekir]

There is significant performance issue on Mac Catalys since commit 3d6dfc5. It also consumes more memory. Its probably same with other platforms. @symbiogenesis can you have a look at that?

[symbiogenesis]

Made a lot of extra performance-related changes since 2.0.0 including:

• Use compiled bindings #77
• Improve performance by setting ItemSizingStrategy #76
• Optimize Reflection #74
• Important performance improvement #68
• Set CompressedLayout.IsHeadless where possible #63
• Make more classes sealed #51
• Reduce bindings #80
• Set colors less #79

I have also fixed some issues such as:

• Column Header is not created when column is created runtime #70
• Crashes on deleting rows from collection #55
• BorderThickness binding on the DataGrid needs to be fixed #53

MAUI itself also has some major issues that they are trying to resolve. This pull request should help when it is merged.

[symbiogenesis]

The memory usage of the CollectionView has been very bad going back to Xamarin.Forms, and they never fully fixed it. There are other issues beyond that recent pull request.

There are multiple collection view projects and branches that try to improve things. Unfortunately, most such projects don't work on every MAUI platform.

See also:

• CollectionView slow/jittering scroll dotnet/maui#12130 (comment)
• Memory leaks EVERYWHERE dotnet/maui#12039 (comment)

Deploying a .NET 7.0 version to nuget may help a little, since only the .NET 6.0 version made it over.

I will do some more testing with the older nuget version to see if I notice any differences between the versions. But I will say that I had seen exactly those kind of issues with the old version.

Because there are enough changes to warrant a new release, I think we should do another release now, and we can keep researching this after.

[symbiogenesis]

I found a way to reliably reproduce a case with bad performance.

My findings so far:

• Reverting the ContentView wrapper: No visible improvement
• Reverting to the DataTemplateSelector: No visible improvement
• Reverting the WeakReference wiring for events: No visible improvement
• Removing the LineBreakMode property: No visible improvement
• Removing the IsVisible binding: No visible improvement

I also tried moving the _headerGrid inside of the HeaderTemplate of the CollectionView. This had no positive impact, but made the header no longer sticky at the top, and thus was worse.

My opinion is that MAUI has internal bugs, and that it potentially even worsened recently.

[symbiogenesis]

I alerted the MAUI team in that memory leaks issue posted above. The developer Jonathan Peppers from the MAUI team is looking into this right now, and found an issue.

EDIT: Here are the PRs which address the issue. Very exciting.

• [controls] fix memory leak in Style and AttachedCollection #13260
• [core] WeakEventManager.RemoveEventHandler() should clear subscriptions #13333
• [controls] one less WeakReference in TypedBinding #13304
• [core] WeakEventManager+Subscription needs IEquatable #13232
• [core] fix memory leaks in bindings #13327

And some other recent performance improvements:

• Let the Grid skip * measurements during the first pass if they'll be overwritten later #13255
• Flag valid measure status in iOS backing views to avoid repeat measuring #12627