Ответ поддержки шторма, в целом, совпал с моей версией:
Could you please provide a screenshot of the energy consumption report of your Mac for the last 12-24 hours?
Meanwhile, here are some common steps.
File | Invalidate Caches | Invalidate and Restart
Follow the steps suggested by File | Repair IDE
Temporarily disable all of the non-bundled plugins and restart the IDE: File | Settings | Plugins | ⚙ | Disable all downloaded plugins
Meanwhile, could you please check in Mac OS Activity Monitor, and see if there is high CPU usage while using PhpStorm?