Subject Simultaneous inserts / selects

do you have any experience in selecting from / inserting to table from multiple threads? Is it faster in comparision to one thread which selects / inserts data in queue?

What is your opinion on this? My gut tells me that it will be always slower in comparision to single thread. But maybe I am wrong and it is worth the hassle to use separate threads?

Assumption here is that each thread pulls of data with different primary / secondary keys and also inserts with different keys.

I would like to hear your opinion about this topic.

Thanks you.