Erratic cores usage

Solution 1:

We see that CPU usage pattern all the time. I wouldn’t worry since that’s what cores should do.

I would focus on one specific app at a time in Instruments if you feel it’s not idling when it should be idle and busy when it should be busy.

Missing metrics from time to time isn’t something that concerns me in general absent other much more telling issues like crashes or stalls. Again, in that case I look at what’s stalling and what’s crashing and not the overall CPU graph to identify what next.

In the context of needing a hardware swap or repair, this is very likely software and if the CPU were having issues, you would have thousands of crashes and issues - not that one graph has missed updates. But, I would absolutely open a case with Apple 2 to 4 weeks before warranty ends to have them run diagnostics of offer you to bring in in for a formal hardware diagnostic. MRI would only show something massively wrong, and you clearly don’t have that, so the only way to test this would be in the shop Apple custom diagnostics that they have, plus getting an experienced tech to load test your Mac.