WWW.bytesDownloaded freeze

When I try to get the bytes downloaded when using Unity's WWW class, it ends up freezing Unity. I've seen the following issue reports and both of them say that it was by design. Why would getting the download progress freeze Unity intentionally?

http://issuetracker.unity3d.com/issues/the-new-www-dot-bytesdownloaded-feature-completely-freezes-unity
http://issuetracker.unity3d.com/issues/www-dot-bytesdownloaded-freezes-application

I'm aware of the www.progress value that I can read, but is there any way to get the specific amount of bytes downloaded without it freezing?

Using Unity 5.2.1f1 Personal on OS X 10.11.1 Attempting to download the 100MB test file found here: http://www.thinkbroadband.com/download.html