About this video

Please forgive the sound cutting out then coming back on. Youtube thinks that one of  the music tracks in this video needs other permissions so I just had the audio deleted for that section to avoid issues
Just some random game play in the Rift which is one of the most resource intensive spots in my game to test for micro stuttering which i was experiencing before.
I have this 3090 running on the ragged edge of what I can possibly cram into this 10 year old game engine.
Things like:

No grass in objects + DynDOLOD 3 and ultra trees
Rudy ENB cranked up with everything turned on except DoF
HDT-SMP hair and clothing for PC and NPC
3BA CBBE body (running the lite version with CBPC)
LOTS of added flora, trees and 4K textures
3440x 1440 resolution

Now this looks amazing but is also highly resource intensive using nearly 100 of the GPU all the time and 15GB of Vram as well as 16+GB of system ram with processor usage around 20% (This last one doesn't mean much in this context since I have a 10 core processor and Skyrim's game engine cannot access all of them).



I was adding HDT-SMP physics enabled items to my already heavily modded game when micro-stuttering appeared which wasn't there before.
I could add KS Hairdo + the Bijin KS hairdo physics replacer along with 3BA CBBE body (lite version using CBPC) , all the vanilla, Dawnguard, and Dragonborn physics enabled clothing and armors plus practical pirate physics enabled armor without stuttering.
Soon as I added in physics enabled cloaks on top of all that the micro stuttering appeared.
It was like an area load stutter where frame rate in the 60s would drop to 30 then climb back up to 60 again only it wasn't only happening at cell boarders.
It also didn't matter if I had a cloak equipped or not.
Cloaks with physics in my LO = micro stutters in my game
Remove the physics patches for the cloaks mods = smooth game play.
I tried a different armor mod not available on Nexus that had a physics enabled cloak thanks to the suggestion of a friend, and it ran without stutters with that enabled and equipped.
So now I'm really curious about 'why' so I open up the .nifs to take a look.
The cloaks that caused stutter were using a full hi poly body mesh (feet and all) for the virtual body to figure out collision.
The cloak that didn't cause stutters was using a very simplified mesh for virtual body in the nif.

Hmmmm, So if every guard and every NPC who is wearing a cloak or cape has to render this hi poly body and the processor has to figure out the collision calculations for every vertice I can begin to understand why this pushed my game over the top and was causing micro stutters.
My second observation was the fluffy cloak from cloaks and capes uses 5 meshes to render that cloak and give it the 'Fluffy' look.
Much like shell texturing employed by fluffy animals mod but on a mesh level instead of the texture.
So now you take all those added collision calculations from the tons of vertices of the hi-poly virtual body and times it by 5 for every fluffy cloak in the scene.

It was mentioned to me that this was a HDT-SMP limitation but I humbly disagree.
Using faster HDT-SMP mod with non-cuda AVX2 DayDreamingDay's code I can run physics body and hair as well as clothing on my character and up to 8 NPCs in scene without stutters, and good frame rate (48+ in Whiterun marketplace).So I don't believe it's the code
I do however think that with everything else I have in my game the cloaks that are not optimized are enough to overwhelm the CPU bandwidth and force the micro stutter in frame rate as it catches up.

Just my observations and thoughts. Your mileage may vary.

My thinking is this is not the mod(s) or mod authors fault but the fact my game is just so packed full of resource intensive stuff that adding this was just a bit over the top of what it could handle.
Here's the cloak on the left in nifskope (look at virtual body mesh) that didn't cause micro stutters. And the cloak on the right that did.
https://imgbb.com/bHqsJv2
Seeing as changing the fluffy cloak to shell texturing from multiple (5) meshes would be about the same as remaking the entire cloak and changing out the virtual body for every cloak and cape then rebuilding ALL the bone weighting as well as re-exporting them all were both things I wasn't going to spend the time on I just scrapped the physics cloaks in my game and using 360 walk run plus for some cloak flair.

The cup is only so big (in this case the game engine) so we choose how to spend our resources for the best bang for the buck.