Complicated Go functions running in main thread might cause ANR (App-Not-Responding) issues

[jyyi1]

We are calling complicated Go functions in the main thread, for example, "Connect" and "Disconnect". This might cause ANR issues if the operation takes too long to complete. Instead, we should start a background thread doing the complicated logic, and only updating the UI in the main thread.

One concrete example is mentioned in #502 .