Backend - is the second part of your two-classes logic component,
which will live in a separated isolate and will have no effect on
the UI thread.
In the Backend, you should place all (heavy or not) your logic and data.
This is the first part of two-class component. Frontend will run in the
UI-thread and its purpose is to update the UI after getting messages from
the Backend or after calling Backend's methods
In some versions of Flutter you can see, that Hot Reload take a
very much time.
See: https://github.com/flutter/flutter/issues/84347
And this:https://github.com/flutter/flutter/pull/84363
To solve this problem - you must have as least isolates
as possible and with this method you can use Isolator in single thread
mode for developing, to have fast Hot Reload as usual and enable
multi-thread (standard) mode only for checking that all works fine
and for production.