doc: add cython extensions to installation page

docs/installation.rst

@@ -4,8 +4,7 @@ Installation
 Supported Platforms
 -------------------
 Python 2.6, 2.7, 3.3, and 3.4 are supported.  Both CPython (the standard Python
-implementation) and `PyPy <http://pypy.org>`_ are supported and tested
+implementation) and `PyPy <http://pypy.org>`_ are supported and tested.
-against.
 
 Linux, OSX, and Windows are supported.
 
@@ -65,7 +64,7 @@ To check if the installation was successful, you can run::
 
     python -c 'import cassandra; print cassandra.__version__'
 
-It should print something like "2.0.0".
+It should print something like "2.7.0".
 
 (*Optional*) Compression Support
 --------------------------------
@@ -94,30 +93,33 @@ support this::
 
     pip install scales
 
-(*Optional*) Sorted Sets
+(*Optional*) blist for Sorted Sets
-------------------------
+----------------------------------
 Cassandra can store entire collections within a column.  One of those
 collection types is a set.  Cassandra's sets are actually ordered
-sets.  By default, the driver will use unordered sets to represent
+sets.  By default, the driver will use a pure Python ordered sets to represent
-these collections.  If you would like to maintain the ordering,
+these collections.  If you would like to use an optimized implementation,
 install the ``blist`` library::
 
     pip install blist
 
+* Note: blist performance is not necessarily better for simply querying sets.
+The only benefit may come with doing set logic in results processing.
+
 (*Optional*) Non-python Dependencies
 ------------------------------------
 The driver has several **optional** features that have non-Python dependencies.
 
 C Extensions
 ^^^^^^^^^^^^
-By default, two C extensions are compiled: one that adds support
+By default, a number of extensions are complect, providing faster hashing
-for token-aware routing with the ``Murmur3Partitioner``, and one that
+for token-aware routing with the ``Murmur3Partitioner``,
-allows you to use `libev <http://software.schmorp.de/pkg/libev.html>`_
+`libev <http://software.schmorp.de/pkg/libev.html>`_ event loop integration,
-for the event loop, which improves performance.
+and Cython optimized extensions.
 
 When installing manually through setup.py, you can disable both with
-the ``--no-extensions`` option, or selectively disable one or the other
+the ``--no-extensions`` option, or selectively disable them with
-with ``--no-murmur3`` and ``--no-libev``.
+with ``--no-murmur3``, ``--no-libev``, or ``--no-cython``.
 
 To compile the extensions, ensure that GCC and the Python headers are available.
 
@@ -133,6 +135,23 @@ On OS X, homebrew installations of Python should provide the necessary headers.
 
 See :ref:`windows_build` for notes on configuring the build environment on Windows.
 
+Cython-based Extensions
+~~~~~~~~~~~~~~~~~~~~~~~
+By default, this package uses `Cython <http://cython.org/>`_ to optimize core modules and build custom extensions.
+This is not a hard requirement, but is engaged by default to build extensions offering better performance than the
+pure Python implementation.
+
+This build phase can be avoided using the build switch, or an environment variable::
+
+    python setup.py install --no-cython
+    -or-
+    pip install --install-option="--no-cython" <spec-or-path>
+
+Alternatively, an environment variable can be used to switch this option regardless of
+context::
+
+    CASS_DRIVER_NO_CYTHON=1 <your script here>
+
 libev support
 ^^^^^^^^^^^^^
 The driver currently uses Python's ``asyncore`` module for its default