I had a error with my client today after the patch and while trying to fix it I stumbled upon this handy tool that gets rid of the wasted space by the poe client. My vm running windows 7/poe client/Eb is now at 14gig hd space. https://www.pathofexile.com/forum/view-thread/28060
It's definitely a useful tool, although it's a good idea just to do a fresh client install each major update due to the number of changes.