I did the test several times with floats on my machine and the difference is not as big as for integers:
==> "i = i + 1.0" is 0.732% faster than "i += 1.0". It seems normal as the float addition is supposed to be slower than integer addition, thus the syntaxic difference is comparatively less important. -- http://mail.python.org/mailman/listinfo/python-list
