2.0 uses a new sampling system for smoother results on effects, this means Mine-imator renders the same frame multiple times according to your "Samples" setting in your render settings. (Can find in the "Project properties" tab and changing the "Render settings" dropdown to "Custom".) Mine-imator 2.0 also introduces more intense rendering effects such as reflections and indirect lighting. The next pre-release will aim to improve rendering times, but rendering will never be as fast as 1.2.9 or 2.0 Pre-release 4 from here on unless you turn off effects and reduce samples to 1.
For example, if you have "Samples" set to 64 and all the new effects(Reflections, indirect lighting) enabled, you can assume it'll take more than 64 times what it used to take to export animations in Pre-release 4.