Last time I looked NewRelic's PHP experience wasn't quite there. Blackfire has been advertising an APM for ages but when I checked in April it still wasn't released to everyone.
The one which never seems to appear on Google when people go looking for one is https://tideways.com/. I've used it multiple times with clients and it finds the problems in minutes.
Another up-and-coming PHP profiler is from DataDog. Again, not a dedicated PHP tool like Tideways so I found the experience lost out a bit (plus the per-server pricing didn't work for us with multiple machines in a HA setup)
The one which never seems to appear on Google when people go looking for one is https://tideways.com/. I've used it multiple times with clients and it finds the problems in minutes.
Another up-and-coming PHP profiler is from DataDog. Again, not a dedicated PHP tool like Tideways so I found the experience lost out a bit (plus the per-server pricing didn't work for us with multiple machines in a HA setup)