45-55% FPS Reduction using 1.21.5 compared to 1.21.4

I originally opened this as a bug report on Github, but I'd figure I would also put it here just incase: https://github.com/IrisShaders/Iris/issues/2732 The TDLR though is, fps seems to be around 45-65% of where it used to be in 1.21.4 (performance varries from different specs it seems). This only occurs when a shader is enabled at all, even disabling it (with the hotkey in my case) causes my fps to be normal like how they are in 1.21.4, 3 other people in this thread is having the same issue, and it seems that (if they are to be believed), there are another 8 people having the same issue too that are just casual players. The difference this time (and I will update this in the bug report too later) is that the fabric1.8.12snapshot.jar does not solve this issue, I'm still getting the same FPS loss. This marks the affected versions now to 1.8.10-1.8.12snapshot for 1.21.5. I'd like to know if anyone here is having similar issues (it doesn't look like to me this thread is a duplicate since the other threads regarding fps issues is not what I'm talking about in this case). I think it varries spec to spec too which is what makes this more difficult, and I'm using an Nvidia 1060 3GB GPU which complicates things since that snapshot.jar mentions AMD performance fixes.
GitHub
45-55% FPS Reduction using 1.21.5 compared to 1.21.4 · Issue #2732...
What happened? Unsure if it could be related to Sodium as well, but performance with shaders in 1.21.5 is halved (at least with my specs) compared to 1.21.4 despite higher fps average without shade...
25 Replies
Samalando (ping on please)
This is an issue with vanilla 1.21.5
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OP2w ago
How much so? Because Vanilla 1.21.4 to 1.21.5 has no performance difference Vanilla isn't really affected so you'd have to explain where it would be affected.
Samalando (ping on please)
there have been lots of people reporting a performance regression, it seems to be some prep for vibrant visuals
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OP2w ago
maybe, i can see adding features that it would need now (to some extent) but the problem is they're likely using an internal build for that. breaking vanilla rendering for a minor patch is pretty questionable to say the least and vanilla rendering is not affected negatively from what i can tell, i can test vanilla just to make sure. i got to get rid of fabric loader though
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OP2w ago
wtf? i thought 1.21.5 was an outlier or result of some fabric optimization update or sodium update.
No description
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OP2w ago
i literally had to double check to ensure i wasn't running fabric loader on 1.21.5 but then that begs to question, i should not be going from 55-70 fps on 1.21.4 to 23-25 on 1.21.5, indicating something is probably wrong not saying im expecting more fps either, i should be hovering around the same
IMS
IMS2w ago
fabric isn’t a mod fyi it’s literally just a transparent loader and can’t touch the game There have been many reports of Vanilla 1.21.5 graphical issues they’re going all in with the rewrites
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OP2w ago
how much of the rendering engine has been rewritten would you say?
IMS
IMS2w ago
a large amount
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OP2w ago
it does seem like a significant amount atleast i see
IMS
IMS2w ago
and they’re only starting
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OP2w ago
well that definitely explains it
IMS
IMS2w ago
1.21.6 already has a lot more
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OP2w ago
but this is defintiely for the better ill try and bear with it
IMS
IMS2w ago
ImmediatelyFast will help with some of the loss
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OP2w ago
because there seems to be no point in fixing this for now if its going to be changed a lot again in the future let me check if that mod was enabled rq nah im hovering the same amount well thats just how it is i guess
тихоня
тихоня2w ago
well, that's just mojang not really iris problem
shibaHacziX
shibaHacziX2w ago
We should be happy that Minecraft is finally stepping in the right direction (Or at least it seems)
Ming
Ming2w ago
According to the recently released note by mojang they are replacing some rendering pipeline and cause the performance lost
IvyLunar
IvyLunar7d ago
I have the same issue too
Slooshie
Slooshie7d ago
Feel free to share your findings on the open issues on mojang’s bug tracker
Nova
Nova6d ago
If anything. on 1.21.5 i am getting higher FPS. its kinda odd
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OP3d ago
^ its because vanilla rendering code got rewritten explains both 3x increase performance in vanilla rendering and 1/2 performance with shaders on i would like to update this topic, it appears that fps is very good in the nether why exactly? im not sure, but its worth noting
тихоня
тихоня2d ago
nether is smaller than overworld same with end dimension
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OP2d ago
ya but the thing is i get 30 fps at render distance 2 in the overworld so its not that

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