This is by now a bit of old news. But I am going to spend more time on this blog updating and releasing more of my code onto the interwebs. So here it is. Autodesk Maya has released a new python friendly API since their Maya 2013 release where you can easily access by importing their module 

import maya.api.OpenMaya as api
To this effect, they claim that using their python api is virtually 2 to 3 times faster than using their old api version. Remember that the original API is a python wrapper over their C++ and had to use MScriptUtils to get around the differences between the C++ and python language differences.

pPos= cmds.xform(parent, q=1, ws=1, t=1)
cPos= cmds.xform(child, q=1, ws=1, t=1)
pVec= api.MVector(pPos)
cVec= api.MVector(cPos)
resultVec= pVec - cVec
dist= resultVec.length()
But it's not all that rosy yet. The modules only available are the OpenMaya and OpenMayaAnim. So we are not able to fully port our code into the new API version. This refers to even the current maya version 2015.

It would be interesting to see, as I personally do not like to use pyMel as my findings are that it is too slow, albeit easier to write with. (Honestly, if you had a heap of your own python utilities to deal with the MScriptUtils you would not need to go through pyMel, it is virtually a wrapper over a wrapper, and a third party plug.)

By the way, using MEL to execute certain things, that I have found are still faster.