It just puzzles me that if a single subprocess spawns a task, meaning that only one task is active, and that task is only accessed by the worker creating it, the massive slowdown happens

That makes sense. You should generally have only 1 task (initialized in the master process). The other subprocesses will inherit this task which should speed up the process

It seems that running Task.init() outside in the main process before spawning multiple processes, and calling Task.current_task() inside the rank = 0 process works with no slowdown

Hi Eugen
Thanks for the response!
let me know if you need a running example, that will require some effort to produce.

Hi @<1671689458606411776:profile|StormySeaturtle98> ! Do you have a sample snippet that could help us diagnose this problem?