> ...about just shifting from PHP to a more performant language
We already shift lots of things out of PHP into more performant (c++, java, etc) languages when we are building services and/or extensions and/or other computationally intensive things.
But I think more to your point (and if not, let me indulge in the strawman), since this comes up frequently on reddit/hn: php is not somehow -uniquely- broken. While PHP might be uniquely broken as a language (ha ha), it's not -uniquely- broken as a platform/runtime. Everything you think is performant is broken at a large enough scale. Put another way, it's not just about the switching costs of rewriting in some other language. If we could magically snap our fingers and convert the entire codebase from php to some other language, that's just the beginning of understanding, tweaking, and occasionally rebuilding everything about the runtime/libraries/etc to make it work.
At the end of the day the language itself is given way too much attention in discussions like this.