Added some benchmarking results.

docs/source/benchmarking.rst

@@ -0,0 +1,30 @@
+.. _benchmarking:
+
+************
+Benchmarking
+************
+
+This section provides information and results from performance benchmarking of gprMax.
+
+How to benchmark?
+=================
+
+The following simple model is an example (found in the ``tests/benchmarking`` sub-package) that can be used to benchmark gprMax on your own system. The model contains a simple source in free space.
+
+.. literalinclude:: ../../tests/benchmarking/bench_100x100x100.in
+    :language: none
+    :linenos:
+
+
+
+
+Results
+=======
+
+Mac OS X
+--------
+
+.. figure:: ../../tests/benchmarking/results/MacOSX/Darwin-15.3.0-x86_64-i386-64bit.png
+    :width: 600px
+
+    Execution time and speed-up factor plots for gprMax (v3b21) and GprMax (v2).