diff -r da483bda6efc README
--- a/README	Mon Aug 24 16:17:13 2015 -0400
+++ b/README	Mon Sep 07 13:09:47 2015 +0300
@@ -173,6 +173,11 @@
 build your desired target.  The interpreter executable is built in the
 top level directory.
 
+If you need an optimized version of Python, you type "make profile-opt" 
+in the top level directory. This will rebuild the interpreter executable 
+using Profile Guided Optimization (PGO). For more details, see the
+section bellow.
+
 Once you have built a Python interpreter, see the subsections below on
 testing and installation.  If you run into trouble, see the next
 section.
@@ -185,6 +190,31 @@
 interpreter has been built.
 
 
+Profile Guided Optimization
+---------------------------
+
+PGO takes advantage of recent versions of compilers, both GCC and Clang. 
+If ran, the "profile-opt" rule will do several steps. 
+
+First, the entire Python directory is cleaned for temporary files that 
+may resulted in a previous compilation. 
+
+Then, an instrumented version of the interpreter is built, using suitable 
+compiler flags for each flavour. Note that this is just an intermediary 
+step and the binary resulted after this step is not good for real life 
+workloads, as it has profiling instructions embedded inside. 
+
+After this instrumented version of the interpreter is built, the Makefile 
+will automatically run a training workload. This is necessary in order to 
+profile the interpreter execution. Note also that any output, both stdout 
+and stderr, that may appear at this step is supressed and errors will not 
+adversely affect the results.
+
+Finaly, the last step is to rebuild the interpreter, using the information 
+collected in the previous one. The end result will be a the Python binary 
+that is optimized and suitable for distribution or production installation. 
+
+
 Troubleshooting
 ---------------