Hi Aman, unfortunately there is no deep and specific performance testing information published in the documentation. I would argue that it would be extremely difficult to provide specific guidance due to the high number of variables that exist within any single DevTest implementation.
Having said that, the basic concept from a Test Automation view is that one spins up Coordinator and Simulator servers under a Registry to execute the tests and generate the desired number of concurrent virtual users (the load). As a general rule, one Simulator can support up to 250 virtual users. The actual number supported by a Simulator is driven by the environmental factors (OS, RAM, CPU, etc) as well as the design and complexity of the test case. Multiple Simulators can communicate with a single Coordinator.
The number of virtual users, the spread of these users across the available Simulators, the length of time that the test executes, ramp patterns, and all the performance characteristics can be specified in the Staging Document. And, the test case or suites provide the actual test case execution steps.
The user's guide does offer some discussion about load and performance server sizing
System Requirements - DevTest Solutions - 9.1 - CA Technologies Documentation
Load and Performance Server Sizing - DevTest Solutions - 9.1 - CA Technologies Documentation
it is NOT a good idea to performance test using the OOTB Derby database. Follow the documentation and connect to an enterprise database.
As the documentation states, once you get the environment setup, run several load tests to find the optimum configuration.