It's a bit unclear on why you're using JSON to pass things between main code and the task itself. I can imagine serializing/deserializing that takes quite a bit

It's a bit unclear on why you're using JSON to pass things between main code and the task itself. I can imagine serializing/deserializing that takes quite a bit of CPU time compared to if you just passed native data structures, or at least something binary instead of a format meant for human introspection.