[IOS] Launch performance

[NielsKnaap]

Description

For the past few months I've been comparing Xamarin.forms and .NET MUAI.
Among other things, I looked at the startup speed of the application on iOS and Android.

To make the differences clear, I developed the same application for Xamarin.forms and .NET MAUI.

For Android I used the script from jonathanpeppers. Here I did indeed see an improvement as you point out in the latest devblog and in the readme from jonathanpeppers.

Now there is little to be found about the performance of iOS. I used Xcode instruments here to measure the startup speed of the applications. My results indicated that the .NET MAUI application launches 9% slower. After that, I zoomed in on the different startup components, which showed the "WillFinishLaunchingWithOptions" component to take 235 times longer:

Activity	Xamarin	.NET MAUI
Launching – UIKit Initialization	0.0240342s	0.02698242s
Launching – UIKit Scene Creation	0.0003936s	0.00042555s
Launching - WillFinishLaunchingWithOptions	0.0000899s	0.02119327s
Launching - DidFinishLaunchingWithOptions	0.2511294s	0.24910752s
Launching – Initial Frame Rendering	0.0233976s	0.03332989s

I see the same result when I create a new "Xamarin.forms blank" project and compare it with a new .NET MAUI project.

Now I don't know enough about what happens in this startup part. But was wondering if this is known? And what could make such an impact on the WillFinishLaunchingWithOptions?

Steps to Reproduce

1. Create a new Xamarin.forms blank project
2. Create a new .NET MAUI project
3. Add development certificate for provisioning
4. Build and deploy to physical iOS device (I used a iphone 7 on iOS 15.4.1)
5. Use Xcode instrument launch to record a trace file of application startup

Version with bug

6.0 Release Candidate 3

Last version that worked well

Unknown/Other

Affected platforms

iOS

Affected platform versions

iOS 15.4.1

Did you find any workaround?

No response

Relevant log output

No response

[jsuarezruiz]

cc @jonathanpeppers

[jonathanpeppers]

@NielsKnaap I think a better comparison vs the dotnet new maui template would be a Xamarin.Forms template using shell. You could also take out shell & the dotnet bot image from the MAUI template to compare against a blank Forms app.

I also heard that using Xcode/instruments is probably not the right way to go, as it introduces a lot of overhead to the app launching. We don't have docs, but here is the method used for measuring iOS startup for the .NET fundamentals teams' benchmarks:

• Implement iOS startup time tracing performance#2355
• Add --fully-drawn-magic-string option to startup scenario performance#2404

It's using xharness to launch the app normally (no profiler attached), then looking at log messages to get the time. I would do this on a physical device and not a simulator.

Hi @NielsKnaap. We have added the "s/needs-info" label to this issue, which indicates that we have an open question for you before we can take further action. This issue will be closed automatically in 7 days if we do not hear back from you by then - please feel free to re-open it if you come back to this issue after that time.

This issue has been automatically marked as stale because it has been marked as requiring author feedback but has not had any activity for 4 days. It will be closed if no further activity occurs within 3 days of this comment. If it is closed, feel free to comment when you are able to provide the additional information and we will re-investigate.