As previously mentioned, while most people were happy with 1.1, the performance improvements and other features we added ate up memory that not all users had available which in turn cased out of memory and other problems for those users.
Rather than simply remove the caching and other performance boosts, we re-engineered saved games and did intensive profiling to opimize things. So v1.11 should be faster AND use less memory than 1.1.
We also made some AI tweaks and other gameplay tweaks.
You can view the full change log here.
The next stop is v1.2 which is mostly about making modding easier for both modders and users. If you check the library, there's already a lot of really cool stuff available. The modding support in 1.2 will make it much easier to organize mods/total conversions.
You can get 1.11 either through Stardock Central or as a stand-alone download. Have fun!