Not nowadays, for sure. In 2009-2010 it was still something to keep in mind, and careful array handling was common so the it wouldn't baloon hundreds of megabytes for not so large data structures. I wasn't working on big data (tm) at that time, but running database imports via ETL processes in PHP required a few optimization passes.
I really can appreciate nowadays the huge memory and performance improvements that PHP went through from the 5.x days to the recent 8.1 release.
Sidenote: Shout outs to Nikita Popov who came to the scene and revitalized the language for me back then, for his proposals and features implemented in a time when PHP felt stagnant language wise https://www.npopov.com/aboutMe.html#accepted-php-proposals