Over the past couple of weeks I noticed sublime consuming considerably more memory, without any changes on my end. Before it would sit comfortably at ~150 MB with a few dozen files opened, whereas now it's at 600-800 MB when I check the task manager (due to bad performance). From what I can gather it appears to be an issue with the buffer, as any operation that involves moving tabs/files or switching panes increases memory usage. Cycling through the tabs does the trick, as does moving files from pane 1 to 2 or simply switching from pane 1 to 2.
As I mentioned at the beginning, I have been using sublime as is with the same exact plugins, settings and preferences since late 2010. Nothing on my system changed either since beginning of 2011. I also just tried uninstalling sublime and removing all old settings. However just with a clean uninstall I can replicate the issue. It seems every time I move panes, files or the current active buffer, the memory usage increases.
Intel(R) Core(TM) i7-2620M CPU @ 2.70GHz
8 GB RAM, HD3000 GPU
Win 7 x64 SP1 with the latest patches, MSE
Let me know if you need anything else.