Is Python's "values don't change, they get replaced by new ones stored elsewhere" approach what makes it slow?

I would like to see some micro-benchmarks which pin down the bottlenecks.

For example, this minimal benchmark with one variable and a few control structures:

    x=0
    for i in range(int(10e6)):
        if i<50: x=x+1
    print (x)

Runs 5 times slower here than the same in PHP:

    $x=0;
    for ($i=0; $i<10e6; $i++)
        if ($i<50) $x++;
    echo "$x\n";

Tested with:

    time python3 loop.py

Which gives me 0.31s

And:

    time php loop.php

Which gives me 0.06s

A factor of five seems to be roughly the average when comparing Python to PHP for a bunch of different code constructs I tried.