Iris Shaders

Iris Shaders

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Regression: looking down with shaders on iris >=1.8.9 drops FPS significantly (313 -> 80 instead of 342 -> 270)

slonkazoid opened this issue ยท 1 comments

commented

What happened?

On Minecraft 1.21.5 with Iris 1.8.9 through 1.8.11 with Sodium 0.6.12 performs extremely badly when you are not looking directly upwards, along with some slightly lower general performance but that's probably unrelated.

Screenshots

these screenshots were taken using Complementary Reimagined on the Potato preset, no vsync, unlimited FPS, 2 chunks render distance, and the seed 1.

Image
Looking directly down on Minecraft 1.21.4 (Iris 1.8.8)
Image
Looking directly up on Minecraft 1.21.4 (Iris 1.8.8)
Image
Looking directly down on Minecraft 1.21.5 (Iris 1.8.9)
Image
Looking directly up on Minecraft 1.21.5 (Iris 1.8.9)

Log output

https://mclo.gs/Xpek4cn

Minecraft Version

1.21.5

Iris Version

1.8.9+mc1.21.5

Operating System

Fedora Linux 42

What is your GPU?

AMD Radeon RX 6500 XT (also tested with Zink and software rendering)

Additional context

This does not happen to my friend with a 7800 XT on Windows 10

commented

Reproducible.

  • System: Arch Linux
  • Device: Radeon RX 590 GME
  • Driver: mesa 25.1.5 linux-firmware-amdgpu 20250627
  • Tested with: Minecraft 1.21.7 Iris 1.9.1

Using the same world, same position, same rotation, same settings & comparing to 1.21.4, my FPS dropped from ~90 to barely 50. It's really annoying.

Related issue: #2732
It seems that this problem also happens on Windows, but not on every machine.