memory allocation failure

the gui is slowing down, slowing down... then an error message pops up that says 'memory allocation failure. failed to allocate memory.' Then CIV quits. then i open it again and load the game i was playing and now it's running much more quickly and smoothly than before.
This has happened a few times. I wish I knew what was happening, maybe i could just make it always run quick and smoothly
I am running beyond the sword expansion with bug

Because BTS is a 32bit application it's only able to access a certain amount of memory*. Unfortunately, it's also rather terrible at freeing up resources, so Memory Allocation Failures (MAFs) are inevitable if you're playing on big maps with many civilizations. The longer a session goes on, the more likely one will happen, especially in the late game where the map is thoroughly coated with improvements and units.

There's no permanent fix, but if your Mac has less than 4GB of RAM, be sure to close all other applications on your Mac before launching BTS (and consider upgrading). Certain graphics may help also, e.g. 'Single Unit Graphics' and 'Animations Frozen'. Choosing smaller maps and/or reducing the number of AI opponents will also reduce their frequency.

Since the only mod you're running is BUG (and assuming you have 4GB+), I'd imagine the MAFs you're getting are pretty in frequentand not worth worrying about. Just save and relaunch whenever things start to bog down.



* Theoretically this maximum should be 4GB, but it seems to be 2GB on Mac and 3GB on Windows. No idea why.