In some ways they've introduced some powerful features bringing it on par with other languages, but the reality is that performance varies wildly in the real world because opcaches are finicky dependent on the data/request type/frequency and automated GC/circular-reference optimization is far from perfect.
Between HHVM (to effectively make memory growth linear vs logarithmic when approaching higher request concurrency) and sensible opcache tweaks you can make that runtime a bit less stochastic at scale, however if you don't know what you're doing PHP makes it so easy to go in the complete opposite direction without any indications you're running toward a cliff...
In some ways they've introduced some powerful features bringing it on par with other languages, but the reality is that performance varies wildly in the real world because opcaches are finicky dependent on the data/request type/frequency and automated GC/circular-reference optimization is far from perfect.
Between HHVM (to effectively make memory growth linear vs logarithmic when approaching higher request concurrency) and sensible opcache tweaks you can make that runtime a bit less stochastic at scale, however if you don't know what you're doing PHP makes it so easy to go in the complete opposite direction without any indications you're running toward a cliff...