uses-sdk-xml element order in ApplicationManifest.xml causes lag

[Laumania]

Steps to Reproduce

1. Move the <uses-sdk .../> element of the ApplicationManifest.xml from the top of the file to the bottom.
2. Rebuild and deploy your app and it lags and have like 50% FPS as before.

Video explaning and showing off the issue in emulator, same issue on real device:
https://www.youtube.com/watch?v=imjRJE8M4dM

Repo found here: https://github.com/Laumania/XamarinManifestBug

Expected Behavior

Order shouldn't matter and if it did, we should be warned.
The problem here is that isn't not obvious and the app still works so it can take a long time until you realize it and then it takes like forever to track back and figure out that it was this element that you moved. Believe me, I was there all Saturday 🗡

Actual Behavior

The app lags (alot!) both on emulator and on real device.

Version Information

Microsoft Visual Studio Enterprise 2019
Version 16.2.5
VisualStudio.16.Release/16.2.5+29306.81
Microsoft .NET Framework
Version 4.7.03190

Installed Version: Enterprise

ADL Tools Service Provider 1.0
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Application Insights Tools for Visual Studio Package 9.1.00611.1
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ASP.NET and Web Tools 2019 16.2.292.25104
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ASP.NET Web Frameworks and Tools 2019 16.2.292.25104
For additional information, visit https://www.asp.net/

Azure App Service Tools v3.0.0 16.2.292.25104
Azure App Service Tools v3.0.0

Azure Data Lake Node 1.0
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Azure Data Lake Tools for Visual Studio 2.3.9000.0
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Azure Functions and Web Jobs Tools 16.2.292.25104
Azure Functions and Web Jobs Tools

Azure Stream Analytics Tools for Visual Studio 2.3.9000.0
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C# Tools 3.2.1-beta4-19408-03+2fc6a04980f800c59e8ede97e6ae294ff47d666e
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Code alignment 14.1.107.0
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Common Azure Tools 1.10
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Extensibility Message Bus 1.2.0 (d16-2@8b56e20)
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Fabric.DiagnosticEvents 1.0
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IntelliCode Extension 1.0
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JetBrains ReSharper Ultimate 2019.1.2 Build 191.0.20190603.142841
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Microsoft Azure HDInsight Azure Node 2.3.9000.0
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Microsoft Azure Hive Query Language Service 2.3.9000.0
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Microsoft Azure Service Fabric Tools for Visual Studio 2.5
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Microsoft Azure Stream Analytics Language Service 2.3.9000.0
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Microsoft Azure Tools for Microsoft Visual Studio 0x10 - v2.9.20626.2

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Microsoft Visual Studio Tools for Containers 1.1
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Mono Debugging for Visual Studio 16.2.6 (4cfc7c3)
Support for debugging Mono processes with Visual Studio.

NuGet Package Manager 5.2.0
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ProjectServicesPackage Extension 1.0
ProjectServicesPackage Visual Studio Extension Detailed Info

ResourcePackage Extension 1.0
ResourcePackage Visual Studio Extension Detailed Info

ResourcePackage Extension 1.0
ResourcePackage Visual Studio Extension Detailed Info

Snapshot Debugging Extension 1.0
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SQL Server Data Tools 16.0.61906.28070
Microsoft SQL Server Data Tools

ToolWindowHostedEditor 1.0
Hosting json editor into a tool window

TypeScript Tools 16.0.10627.2001
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Visual Basic Tools 3.2.1-beta4-19408-03+2fc6a04980f800c59e8ede97e6ae294ff47d666e
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Visual F# Tools 10.4 for F# 4.6 16.2.0-beta.19321.1+a24d94ecf97d0d69d4fbe6b8b10cd1f97737fff4
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Visual Studio Code Debug Adapter Host Package 1.0
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Visual Studio Tools for Containers 1.0
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Visual Studio Tools for Kubernetes 1.0
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Visual Studio Tools for Unity 4.2.0.1
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VisualStudio.Mac 1.0
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Xamarin 16.2.0.95 (d16-2@37df81894)
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Xamarin Designer 16.2.0.375 (remotes/origin/d16-2@357d38ef4)
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Xamarin Templates 16.3.117 (59a59e8)
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Xamarin.Android SDK 9.4.1.1 (d16-2/cec9eb4)
Xamarin.Android Reference Assemblies and MSBuild support.
Mono: mono/mono@e6f5369c2d2
Java.Interop: xamarin/java.interop/d16-2@d64ada5
LibZipSharp: grendello/LibZipSharp/d16-2@caa0c74
LibZip: nih-at/libzip@b95cf3f
ProGuard: xamarin/proguard@905836d
SQLite: xamarin/sqlite@8212a2d
Xamarin.Android Tools: xamarin/xamarin-android-tools/d16-2@6f6c969

Xamarin.iOS and Xamarin.Mac SDK 12.14.0.114 (c669116)
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Log File

Description to find logfile didn't work - run the repo and see for yourself.

[Laumania]

Might be related to #1332

[dellis1972]

@Laumania thanks for the comprehensive bug report. We will take a look at this. We are currently considering using the Google manifest merging tooling to deal with this, so it might be fixed as part of that work.

This might have something to do with the way android processes the Manifest file at build time, I suspect what might be happening is the uses-sdk is not being picked up so you end up in a compatibility mode where your minSDK will be 1. That might cause the performance issues.

[Laumania]

@dellis1972 Thanks for the quick reply. Now I know this, and after spending 1+ day on finding the issue, I am NOT doing this mistake again :)
However, guess many others might - looking forward for a fix for this.

Happy coding!