Enable xdebug profiling temporarily while you profile. You’ll kill a ton of disk space if you leave it on.
Install qcachegrind from homebrew (brew install qcachegrind)
By default cachegrind output files go to /var/tmp (I think).
Move somewhere useful. Open qcachegrind to read this file. It’s in:
/usr/local/Cellar/qcachegrind/18.04.1
Spotlight didn’t find it, so maybe create a symlink or something elsewhere.