Flutter platform-specific code: Android broadcast receiver response is slower than native android

I am working on a project that requires BLE connection. There is a feature that I could not do with plug-in so I had to write platform-specific code.
This feature is performing OTA DFU using BLE. This feature requires Access to Broadcast Receivers to communicate with BLE devices.
The problem is Brodcast receiver response time is slower than native android. I build the platform-specific code with a separate android project it took 28 sec to complete the whole DFU but with flutter platform-specific code took 3.30 minutes.

So my question is, am I doing something wrong or this is a known issue for flutter.