What does com.apple.CoreSimulator.CoreSimulatorService do?

Question

Our simulator iOS tests on the simulator survived the disaster from the time we upgraded to Xcode6. We can observe a slowdown in substitution, UIAutomation also felt this and often returned an empty or not fully updated main application window, you can imagine stability.

Part of the reason is that we have slow virtual machines, but we still need to find ways around them.

Then I notice that the CoreSimulatorService process stays alive between starts and shutting down the simulator. So I killed him to see what he would change:

killall -9 com.apple.CoreSimulator.CoreSimulatorService 

After he was killed and restarted, the simulator's performance seemed to get much better, at least I no longer see random crashes (hopefully). I think this is partly a cleanup.

So, I hope to get a better idea of ​​what function CoreSimulatorService performs?

Also, I'm confused about where to look for documents when Apple releases new things (forgive my ignorance). For example, I did not find any documents mentioning simctl in the iOS developer library except Xcode Release Note.

Thanks!