You never really finish Skyrim. Sure, you might have finished the main quest, ploughed through the DLC, clocked in hundreds of hours faffing around with random mini-quests and installed hundreds of mods, but you're only ever taking a break until the next special something gets put together.
Today's special something comes courtesy of ENB forum user sheson, who has figured out a way to allow Skyrim to allocate blocks of memory greater than 256MB, potentially allowing for gigantic battles with 300+ NPCs on the screen as well as increase the stability of more memory intensive mods.
The sky is the limit, apparently, but it's only recommended that you increase the first block to 512MB and leave the second one alone and this mod still requires extensive testing. It's possible to increase both blocks to 768MB, but like many of the more extreme visual mod combinations, it's only really practical for taking gorgeous screenshots.
"When tesv.exe is started it allocates two 256MB blocks of memory. When the first block gets full, the engine will allocate more blocks. This can cause the known troubles. Thankfully, by telling the engine to request a bigger block from the start it magically makes use of it without any further ado. This isn't the case with the second block. Thankfully again, the second block does not fill up as quickly and once it is full the engine does not trip over itself when allocating more blocks."
You can check out a detailed list of instructions here.