Pypy builds faster if using -O2 option.
To build faster (according to pypy documentation) use prebuilt pypy from link
Using virtualenv to create virtual environment for it.
Build script (to be placed in pypy source directory):
#!/bin/bash
cd pypy/goal || exit 1
source <path to existing pypy environment>/bin/activate || exit 2
pypy ../../rpython/bin/rpython --batch -O2 targetpypystandalone