Anything more than that and we risk impacting the performance of user queries.
Well, unbounded bloat will also impact the user queries--eventually. Was this an experimental determination? Can you tell what about the autovac most impacts the user queries, the reading or the writing?
You might just have more workload than your hardware can handle. There is always going to be some fundamental limit, and while you can tune your way up to that limit, you can't tune your way past it.
