One of the major change that adobe had made is that they had included a Protective Mode in it.From a long period it has seen that hackers use PDF documents to spread malaises files and whenever you open that infected files it may make changes to your current programs, registry and may be in system files.
So Adobe had introduced Protective Mode in this version,it allows you to run those programs/script but it will not affect you computer.
But sometime it may delay or takes some great time to open your files.So you may want to disable it, as it is enabled by default.
So if you wanna disable it then here it is the process :-
Open you Adobe Reader and and Preference by clicking on Edit –> Preference Or just press Ctrl + K,
Now goto under General Tab,
Here you will see an option of Enable Protected Mode at Startup, just Check or Uncheck it according to your need.