Slitherine

I got into a stalemate situation on the Guardians of Steel mission where I went through thousands of units. My framerate started around 100 FPS, and by the time I gave up I was getting 6 FPS. I suspected a memory leak of some form, but restarting the game/computer didn't fix it. What DID fix it was loading much earlier saves. Opening the later saves always resulted in terrible FPS. I cracked open the save files and found that my latest save was about double the size of my final saves in earlier missions. Looking inside, it seems like there may be data stored about every unit I lost throughout the course of the mission. I tried deleting all units from the save, and got it working, but then it triggered the "officer has died" failure condition (despite me being way beyond that stage of the mission). At that point I gave up and just used the "kill" command on the hives to complete the mission. Framerates in subsequent missions are back to normal.

@Slytherine I've attached a zip containing my dxdiag, options, and a save game that reproduces the problem.

(Not sure the attachment actually stuck; please let me know how to send it your way if you need it)