Haters gonna hate, but well-written JS performs better than most php software.
From shit ass slow angular websites to instant loading react ones, there just can't be a generalization. You have awesome software like Atom written in node and I bet many people would never realize it was written with Node.js.
We also have a lot of proprietary crap (look at IBM/MS stuff) written in C and now Java which are slow as a turtle. Node by itself is a fine tool and it sure does help me build better websites.
Just don't think a MEAN platform is gonna be the best for everything. I've often used node with PostgreSQL, for example, because it was a better combination for the job. The same applies for LAMP, it's not snake oil. Know your tools and use them wisely and you'll be fine with whatever path you pick.