In the case of tokio, multiple actors can run on a single thread. Tokio uses a worker pool of threads equal to the number of cores on your system. So spawning a new actor will run amongs other actors. This lets us perform io operations in an actor, such as http connection, and progress other actors whilst waiting for a response.
Kameo does have a `spawn_in_thread` function for CPU bound actors if needed.
Kameo does have a `spawn_in_thread` function for CPU bound actors if needed.