<i>why has Python 3 adoption been so slow?</i><p>I can tell you about our situation.<p>We are an animation studio with decades of legacy Python 2 code.  We sponser pycon and are one of the poster children for python.<p>We have absolutely no plans to switch to Python3.<p>Here are the various reasons:<p>- Performance is a big deal, and moving to a version of python that is slower is a no-go off the bat.<p>- Python3 has no compelling features that matter to us.  The GIL was the <i>one</i> thing that should have been tackled in Python3.<p>- Since the GIL is here to stay, our long-term plan will likely involve removing more python from the pipeline rather than putting a huge effort into a python3 port.<p>- We have dependencies on 3rd-party applications (Houdini, Maya, Nuke) that do not support Python3<p>- We have no desire to port code &quot;just because&quot;.  Each production has the choice of either spending effort on Real Features that get pixels on the screen, or on porting code for No Observable Benefit.  Real Features always win.<p>- Python3 has a Windows-centric &quot;everything is unicode&quot; view of the world that we do not care about.  In our use case, the original behavior where &quot;everything is a byte&quot; is closer to UNIX.  A lot of the motivation behind Python3 was to fix its Windows implementation.  We are a Linux house, and we do not care about Windows.<p>- Armin&#x27;s discussion about unicode in Python3 hits many of the points spot on.<p>Why has adoption been so slow?  Simply because we have no desire to adopt the new version whatsoever.  We&#x27;ll be using Python2.7 for _at least_ the next 5 years, if not more.<p>It&#x27;s far more likely that we&#x27;ll adopt Lua as a scripting language before adopting Python3.