When the concurrent number reaches 10, the response time is very slow. Is there any configuration that Zeebe can optimize?
Could you please share a bit more information on your scenario, stack, environment (cloud or self-managed)? Also what runs concurrently (starting process instances, workers, …) and where exactly does it get slow? And what does slow mean in numbers? Do you see any exceptions (e.g. around back pressure) or the like?
In order to comment on this, we would need more information. In general, we do have users running quite big loads, with a lot of instances in parallel.
For example, you might also face a problem of your workers not parallelizing work, e.g. because you are doing synchronous programming. See also https://blog.bernd-ruecker.com/writing-good-workers-for-camunda-cloud-61d322cad862
Watch the video and examine the spreadsheet in this forum post: New Zeebe Performance Benchmarking Tool
Performance tuning Zeebe for your use case will involve running multiple experiments, tracking all of the factors, and seeing how each factor influences the performance.