The heaviest part of executors are the task queues and the threads themselves. If you're using 2 or 3 executors over a single one, you're presumably using the s

The heaviest part of executors are the task queues and the threads themselves. If you're using 2 or 3 executors over a single one, you're presumably using the same amount of space in the queue and number of threads, so the "weight" doesn't change except that the queues are concurrent data structures so can be sources of contention ... in really odd hyperactive scenarios. Executors tend to be units of management (await()/shutdown()) etc. and monitoring, so that'll be your main reason to use more than just one for everything.