Seeing the exact same issue here. Wondered why I was constantly hitting high CPU usage, crash reporter constantly spitting our reports for MercuryPosterExtension.

Yeah there's an ongoing disucssion about this here. I've also filed it under FB20925624. It seems to be due to the process that loads the simulator's background image crashing over and over and over. I haven't found a way to prevent it yet. ReportCrash is going to keep spawning while the crash is happening.