Unfortunately there are too many bugs and bug reports for me to find if these have been reported before.  I think these bugs are related and hint at some of the problem.

First, the Out of Memory crashes ... it seems obvious there are some memory leaks, as after several crashes, I started running Windows 7's Task Manager with the Performance tab running so I could see what was being used up to the point of the crash, and its generally near 100% on one core's CPU (which I guess is to be expected ... with as big and new an engine that Elemental is, would have been nice for it to have multi-core support though) and nearly 4 GB on the "Commit Charge."  I have 4 GB of system RAM, and the Windows Swap File seems to about double that for 8 GB available memory, and Elemental crashes with Out of Memory when it reaches near the 4 GB mark.  If I restart the game, load the autosave (I have it set to save every turn now), and just after loading Alt+Tab out to check the Commit Charge, its only around 1.5 GB.  The same game, reloaded, and it is using less than half the  RAM it did after it had been running awhile.

There have been a number of other relatively minor bugs that also hint at a memory leak.  The mini-map freezes and will not update graphically sometimes -- I can click and drag through it and it will actually move the screen, but the map it shows is frozen, the red 'what you are looking at' pseudo-rectangle will not move and areas I have uncovered remain black with fog-of-war.  It will generally work again if I save, exit, restart Elemental and reload the game.  However, if I abandon the game and start a new one, the mini-map will still show the old frozen one from the previous game.

That's not the only thing that tends to stay from the previous game, either.  If I've researched advanced Military technology to make Veteran troops or grouped units, my cities in the new game on their "Recruit" tab will have those options lit even though I don't have the required research technology.

I hope this helps point the way to some of the memory leak issues where the game engine isn't releasing variables that it should.