Are there large delays in the message queues?

Question

RabbitMQ

I want one microservice to transfer information to another. I understand that a message queue is used for this (for example, rabbitMQ). What could be the delay? Is it possible to keep a message queue somewhere in memory?

Answer 1

What could be the delay?

Depends on the config and disk speed. Usually not critical. Maybe about a few to ten milliseconds (did not measure).

Is it possible to keep a message queue somewhere in memory?

Do you mean save to disk? Yes, you can:
https://www.rabbitmq.com/persistence-conf.html
Well, this is specifically about rabbitmq. Other brokers may be different.