[net6] mono_threads_enter_gc_safe_region_unbalanced performance regression

[jeromelaban]

Steps to Reproduce

Invoke UIView.get_Superview in a loop.

Xamarin:

.NET 6 RC1:

My guess is that it is caused by changes in mono_threads_enter_gc_safe_region_unbalanced, but I'm not completely sure.

Expected Behavior

Performance is similar or better than Xamarin.iOS.

Actual Behavior

Performance is slower around 20%.

Environment

.NET 6 Mobile RC1

Build Logs

Example Project (If Possible)

[rolfbjarne]

This could be: dotnet/runtime#58939

[chamons]

As noted in that issue:

Fixing/improving this would require risky changes so this will unlikely to be fixed for 6.0.

[jeromelaban]

That's a good thing that 7.0 is not yet out, isn't it? :) Tasteless joke aside, this is an issue that will lower the quality of iOS applications for people migrating to .NET 6, even if the offset of performance of iPhones can make this less relevant on newer devices.