I still think you are not factoring in the processing time of this package, which is not the same as the refresh rate interval. This package is for handling heavy jobs on separate processes, I don’t think it designed for handling near-real-time jobs with very low latency.
I’ve not used it but my feeling is that it has processing latency and it is the culprit in your problem since this is where you diverge from a typical pub/sub, but that is my intuition, I might be wrong, just trying to help.
As for the concurrency, so you mentioned the following in your other post:
Where is the job collection being stored? is it in memory at that synchronization/pulse server?