Why would we think php is slow? PHP is blazing fast certain applications (looking at you sugarcrm) make this into a mockery by rewriting queries and loading unnecessary data into each page request.
Nice to see a php related show and tell.
It's still quite slow compared to C/C++/Rust/Go, more than 10x slower:
https://benchmarksgame-team.pages.debian.net/benchmarksgame/...
That same benchmark shows JS code that’s 6x faster than PHP.
PHP was popular when it had MySQL bindings that were always up to date with MySQL changes and apache PHP setup was simplistic. Thus the LAMP stack, right? It has always been rather fast, in the larger ecosystem of web scripting languages (especially if you avoided particular BIFs) but it got a LOT faster in 7 as the slowest bits were optimized alongside everything else.