The latest version of Concrete5 is 5.6.1, it was released on Feb. 14, 2013. One of the major improvements was with performance, resulting in some significant speed increases, this will please visors to your website. There were updates in the way Concrete5 caches pages, since the Page Caching Library was completely redone, this can make load times quicker as well.
The Dashboard area also responds much more quickly, as it connects to the database less often. This will save you time when you are building and updating your site.
As you can see, many of the updates in the latest version of Concrete5 dealt with speeding up the program.
Here is a link to the Official Concrete5 5.6.1 Release Notes.
Click here to view our Concrete5 Education Channel.