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Strange performance problem (Ultra trees much faster than billboards) SkyrimVR



Hi there, I ran into a strange problem.

I am currently redoing my SkyrimVR setup (played the game from mid 2018 - mid 2019 already with 516 mods + dyndolod, everthing fine, but different PC). So I am not completely new to dyndolod and mods.


I asked about this problem on Reddit (Skyrim mods and SkyrimVR) and nobody knew what the solution might be.



The hardware:

i7 9700K, 32GB RAM, RTX 2080ti


The game:

SkyrimVR with 470 mods (basicly the new SIRVAGG 2020 - A New Era



The effect:

In frametimes in miliseconds. I need to stay below 11ms to be judder free in my headset.

Values all at the same spot and directon of view:


1. no dyndolod at all: 5.5 ms

2. Ultra Trees (ini setting and LOD4 far grid) dyndolod medium: 7.0 ms

3. Ultra trees ini setting but forgot the LOD4, so I had billboards): 6.0 ms

4. normal billboard dyndolod medium (looks absolutely identical to the one above, except that above the billboards are too bright): 15 ms (my analysis tool "fpsVR" says, the CPU causes that lag, not the GPU)


So, what is the problem you ask, just use Ultra trees? Thats what I though aswell. But then I added more mods (looks seriousely good now) and now Ultra trees hover around 11 ms too often. Dipping too often over. Reach 13-15ms permanently in some regions.


Ultra trees with leaving that billboar setting results in like 8ms. Wonderfull, if the billboards wouldnt be totaly out of place with their brightness (dyndolod ignores the brightness setting if I flag the ini ultra trees)


Using dyndolod the normal way: 16ms


Some things I found out:


When I am in whiterun market place, with dyndolod normal non-ultra trees setting and look towards the direction of Riverwood: 4ms. Looking towards the castle (there arent even trees eh?): 16ms. Looking toward the castle with Ultra trees: 6ms (but why?  :cry: )


When uninstalling some mods, vagualy related to trees I found one that made a difference: "HD LOD" (HD Lod textures basicly). Removing that one BEFORE the dyndolod calculations resulted in that whiterun castle watching to go to 5ms (instead of 16ms) When i found out, I was happy and thought: yeah, just do it like this.... and it works in like 80% of all places, but the other 20% of places, it goes back to 16ms, while ultra trees manage to be at 9.5ms at the very same places.


I already thought my new PC maybe has a damaged CPU (mainly because I had to drop wireless module for VR, because it caused CPU lag when playing Boneworks (during combat it was 16ms wireless and 6ms with cable). Its known that the wireless module eats tons of CPU, but I cant imagine a i7 9700K cant play boneworks with it? I dont know (still havent removed the Wifi card from the PC through, but the software isnt loaded, so...). A CPU benchmark claims, everything is as fast as it should be.


Anyone has an idea, what this could be?


Edited by Wullaz
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As is well known Skyrim already has a micro stutter problem with tree LOD when the camera crosses cell borders.
From DynDOLOD-Trees.html:
Also consider setting the LOD levels to a Billboard to replace traditional tree LOD by static object LOD billboards instead without using hybrid trees/full models. Traditional tree LOD and high values for fTreeLoadDistance= can cause micro stutter in 3rd person in Skyrim when the camera crosses cell borders and the vanilla 2D tree LOD causes severe FPS loss in Skyrim SE with many plugin installed (fixed by SSE Fixes or SSE Engine Fixes). Using billboards in object LOD is a suitable fix as well with the added benefit of better lighting control etc.
With Skyrim Special Edition it got worse with the infamous nested loop together with many plugins, which got fixed by SSE Fixes and then SSE Engine Fixes.
In addition, pre-computed object LOD meshes with just more triangles beat the tree LOD system which builds the 2 planes for each tree on the fly and which tries to match form ids to references to know which tree LOD to disable when cells attach. With the known bugs of "stuck" tree LOD in walled cities or if the load order of plugins changes.
More triangles in a object LOD mesh is not much a problem with recent (last decade or so) hardware. The archaic tree LOD system is from times/platforms for which memory was of higher concern.
DynDOLOD does not "ignore" the tree LOD brightness setting. It is always applied to tree LOD billboard textures before they are added onto the tree or object LOD atlas.
In addition you can always manually edit billboards, the generated texture atlas to adjust things after the fact. You can also make use of the FlatLODVertexColor setting or use External billboards to control things in detail.
3D tree LOD models typically do not need a brightness adjustment, since the branches and leafs are copied 1:1 from the full model (depends on tree mod of course, but maybe give vanilla trees a test for comparison) and thus react the same to all lighting conditions as the full models, as explained in DynDOLOD-Trees.html
Minus shadows of course, since LOD does not cast or receives shadows. ENB "distant shadow" effect mitigates that.

Edited by sheson
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Thank you for the reply.


I think I need to try to darken LOD billboards. (I already checked if I can just open them in photoshop, but... I couldnt. At least not in that version I still have.

I dont know if all the trees have this problem. Maybe the problem is mainly the pines. I use a dark texture for them, not the default one. That makes them dark green. All the static LOD 4 are dark green. But the billbaords are bright green. If I put "-7", they apear about right. But not if I use the ultra tree flag. then "-15" still looks like "0" in non-ultra trees.


I use a VR version of SSE fixes. Yesterday tried SSE engine fixes, but no difference.


Recent hardware may not have a problem with monitor games. But VR is more hardware demanding (roughly as much as 7 years of hardware development gain in performance. Thats the reason why VR games all look kind of vintage in their optic. There is just no hardware that can make the frame rates needed for VR, with modern optics).


I need to render 4320 x 2400 pixels (150% supersampling), 90 frames per second. My problem is, that I only get 70 frames per second. That wouldnt even be a problem on a 60Hz monitor.

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Hmm, where do I edit a post. Doesnt matter.


I just got dark billboards as intented. :-S (through just for pure interest I checked "far grid" for them and put the darkest possible setting and... woot.

I try to work from here. ;-)

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Hmm, where do I edit a post. Doesnt matter.


I just got dark billboards as intented. :-S (through just for pure interest I checked "far grid" for them and put the darkest possible setting and... woot.

I try to work from here. ;-)

If changes to seem to have any affect, it means the newly generated texture atlas is not active or being overwritten by older files. It can also mean the tree you are looking at is not using the texture atlas.

The Near/Far Grid setting only changes the distance at which a dynamic LOD object is shown. The setting does not change models or textures.

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