Describe the bug
After upgrading flutter_bloc to 3.0.0 (and rxdart to 0.23.1) I've noticed slight spike in CPU usage by Android Emulator (qemu-system-x86_64.exe process, Windows 10). Immediately after starting the app CPU usage jumps to 40+% and just stays there even though app does nothing.
If downgraded back to 2.1.1 (rxdart to 0.22.0) and restarting the app it falls to 4-5% and everything is ok.

To Reproduce
Steps to reproduce the behavior:

1. Upgrade flutter_bloc to 3.0.0 and rxdart to 0.23.1
2. Start the app
3. Check CPU usage in task manager

Expected behavior
CPU usage stays low.

Paste the output of running flutter doctor -v here.

[√] Flutter (Channel beta, v1.12.13+hotfix.6, on Microsoft Windows [Version 10.0.17763.914], locale en-US)
• Flutter version 1.12.13+hotfix.6 at C:\flutter
• Framework revision 18cd7a3601 (2 weeks ago), 2019-12-11 06:35:39 -0800
• Engine revision 2994f7e1e6
• Dart version 2.7.0

[√] Android toolchain - develop for Android devices (Android SDK version 28.0.3)
• Android SDK at C:\Users\amunk\AppData\Local\Android\sdk
• Android NDK location not configured (optional; useful for native profiling support)
• Platform android-28, build-tools 28.0.3
• Java binary at: C:\Program Files\Android\Android Studio\jre\bin\java
• Java version OpenJDK Runtime Environment (build 1.8.0_202-release-1483-b03)
• All Android licenses accepted.

[√] Android Studio (version 3.5)
• Android Studio at C:\Program Files\Android\Android Studio
• Flutter plugin version 42.1.1
• Dart plugin version 191.8593
• Java version OpenJDK Runtime Environment (build 1.8.0_202-release-1483-b03)

[√] VS Code (version 1.41.1)
• VS Code at C:\Users\amunk\AppData\Local\Programs\Microsoft VS Code
• Flutter extension version 3.7.1

[√] Connected device (1 available)
• AOSP on IA Emulator • emulator-5554 • android-x86 • Android 9 (API 28) (emulator)

• No issues found!