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...
19 Replies
This is an issue with vanilla 1.21.5
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.
there have been lots of people reporting a performance regression, it seems to be some prep for vibrant visuals
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
wtf? i thought 1.21.5 was an outlier or result of some fabric optimization update or sodium update.

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
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
how much of the rendering engine has been rewritten would you say?
a large amount
it does seem like a significant amount atleast
i see
and they’re only starting
well that definitely explains it
1.21.6 already has a lot more
but this is defintiely for the better
ill try and bear with it
ImmediatelyFast will help with some of the loss
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
well, that's just mojang
not really iris problem
We should be happy that Minecraft is finally stepping in the right direction
(Or at least it seems)
According to the recently released note by mojang they are replacing some rendering pipeline and cause the performance lost