First the good: I recently installed Streamline and in general have found that it in conjunction with Oblivion Stutter Remover has improved performance in my game. Random CTDs seem to be much less common, I'm assuming because of Streamline's purging functions cleaning up things in memory.

I followed the instructions and various guides and made sure that my Streamline FPS numbers were within OSR's. I'm using a range of 20-40 in OSR and the default range of 26-31 in Streamline. Everything seems to work smoothly with respect to FPS numbers, particularly in heavily populated areas outside.

Now for the odd...my normal process is to install one mod at a time, then run around in the game and test for a while to make sure nothing strange has been introduced. Since installing Streamline I have noticed something unusual happening at apparently random times with body parts. For example, I went to a dungeon and a Khajiit's tail had turned into a vector which was attached to an orc's head. This was kind of funny in a way, although even after the actors were killed the line was present. The anomoly also carried over when I tried to save the game and reload...when I disabled the orc as a test the tail instead went through the wall and out the other side through a corridor. Later I went into a guild hall and one of the NPC's shoulders were twice the length of his body. In another case the scabbard on the belt of a dead spectral reaver was also creating a line vector that went off into a wall. Reloading made that go away, however.

I wasn't able to reproduce any of these scenarios with fresh new games and by coc'ing back to those cells, and I have never seen these kinds of graphical glitches before. Streamline seems in general to be an improvement, but given that I've observed these glitches multiple times in a relatively short period after installing it, with a setup that otherwise seemed relatively glitch-free I'm wondering if anyone had any suggestions about any Streamline ini settings I should be checking or altering.

That graphical glitch sound like the mesh loosing or having lost part of it's property. If you have PyFFi:ed your meshes it is a one that got bugged, replace character folder with original in meshes folder.

Now if you haven't PyFFi:ed and as you said it was not reproducible, then it hopefully was just a fluke. It could also be that your GFX-card is having a hard time. If it starts happening more often and not on the same objects I would start looking real hard at the GFX-card.

Long time since I used Streamline but as far as I know it should not produce these kinds of glitches. Crucified NPC's are the most conmen glitch than might appear.
You could also try un-installing Streamline and see if theese anomalies disappears.

Or, if you are using Heapreplace 1 (the borlind.dll) in OSR, try to use an other type, like 3 or 5 instead.

Cheers!

+ 1 I can't see how Streamline could cause those issues. Make sure you're using the patched 3.1 release of Streamline as it fixes other issues - but that's not connected to your current ones.

I can't imagine the connection either. your problem seems to be occurring with meshes, which Streamline doesn't touch I don't think.
The obvious first step, if the problem is still apparent, is to remove Streamline and see if the problem still persists. And if so; if it reappears on reactivation of Streamline.

Thanks for the replies. I didn't PyFFI character meshes, just the ones that are safer to optimize like architecture.

Right now my current theory is that it was just fluke associated with activating Streamline and loading an active test save rather than starting a new game. Since starting a new test game it hasn't recurred. I never add a new mod or even updates on "active" games so I'm planning on starting a new character after I get done with my current build anyway.

I don't think my graphics card was overtaxed since it only happened in interior cells. I have a 5970 and memory usage in those cells was only around 400 Mbytes of my 2 Gbytes of VRAM.

I did try deactivating Streamline and reloading the other test save, which resulted in some even stranger behavior (like when I went back to that cell it was just fog - no walls or anything).

Before adding any additional mods I'll probably play around in the new test game for several hours this weekend just to make sure there aren't any other ghosts in the machine.