HDT causing progressively worse performance. Cause?

[Fredas]

Toying with HDT breast physics.  Without it installed, I get a reliable 60fps.  With it, I start out at 60, quickly drop to the mid-40s, and after about ten minutes it's in the teens and effectively unplayable.  This is with just one character on the screen (the player).  Using the latest version.  Also worth noting that if I save a game after some measure of performance deterioration, when I then load that save, the performance deterioration was also somehow maintained, so that if I saved a game when my framerate was in the 30s, loading that save puts the game immediately in the 30s rather than starting afresh at 60fps.

 

Seems like this may be a known problem with a known solution, so that's what I'm hoping for.

 

[Mud]

The XPMSe post says that in order to use XPMSe 2.0+ with older HDT xmls, you need to open up the Default xml and change any references to NPC PreBelly to NPC Belly instead. Have you tried that?