Very slow performance on debug mode

Is there an existing issue?

• I have searched existing issues

Build info

• objectbox version: 4.3.0
• Flutter/Dart version: 3.29.3
• Build OS: macOS 15.4.1 (24E263)
• Deployment OS or device: Android 14,Android 15, iOS 18.4

I'm migrating from Isar to ObjectBox and facing a major issue in debug mode. I’ve done some investigation but haven’t identified the root cause yet.

I’m already using ObjectBox in another app (Flutter version 3.24.5) without any performance issues during debugging. However, in this other (much larger) app, I’m unable to run it smoothly in debug mode. After some research, I found two possible reasons:

1. Merged platform and UI threads – Flutter issue #150525. This specific comment caught my attention.

2. Hot reload performance degradation when using multiple isolates – Flutter issue #169437

I’ve tried using the following flag:

<meta-data
    android:name="io.flutter.embedding.android.DisableMergedPlatformUIThread"
    android:value="true" />

But the result was the same.

My question is: is this a Dart/Flutter limitation, or is it truly related to the merged thread behavior and FFI communication?

It's also worth noting that I don’t experience this problem with Isar, even though it also relies on FFI.

No repository file, test, or entry point is identified. Start by reproducing the debug-mode slowdown in the larger Flutter app on the listed Android or iOS environments, then compare behavior with the referenced Flutter merged-thread and multi-isolate issues; done requires identifying whether ObjectBox FFI contributes or documenting a Flutter limitation.