[GENERAL] Python versus Other Languages using PostgreSQL

Hello,

I noticed that most of the largest web platforms that use PostgreSQL as their primary database, also use Python as their primary back-end language. Yet, according to every benchmark I could find over the last couple of years, back-end languages like PHP, HHVM, and Node.JS outperform Python by 2x to 8x!

So here are my questions:

1) Why do the largest web applications that use PostgreSQL also use Python, even though Python is significantly slower than it's biggest competitors?

2) Can PostgreSQL just as easily be used with PHP or Node.js? If not, why not?

3) Can PostgreSQL be made to work seamlessly to take advantage of the superior performance of HHVM or Node.js?