Hi there, Recordings done by xctrace will run in deferred mode by default, unless the template is setup to be using windowed mode or you specify window option. Hope that helps! Kacper

Hi Simon, Thanks for your feedback here. First, answering to your questions: There's currently no way of viewing Cores frequency in Instruments, nor lock the frequency of a device. If you could file a new request for this in Feedback Assistant — it'd be greatly appreciated. We try to prioritize depending on users needs, so it helps us track it. We're aware that it's important for the users to have repeatable and stable environment for profiling. The only way of affecting your device condition from the tools are currently: — Condition Inducers in Xcode that allow you to simulate certain device states, — Locking number of CPUs in Instruments (Mac devices only) As far as solving your problem: It'd be interested to put signposts in the code you're measuring to see what's the standard deviation of duration of this operation and try to diagnose whether it's indeed because operation is taking more time. It's also important to take a look at your thread with System Trace / Time Profiler and see whether it's ready to run or maybe being blocked by some other activity on the system. If you're able to capture a trace of your problem — I'm happy to take a look and help you diagnose it. Thanks, Kacper