: Generally works on recent versions of Iris (1.6.x+) and Oculus. Older versions of Iris (e.g., 1.2.1) had significant regressions causing PTGI 3 to fail, often appearing as "default Minecraft". SEUS PTGI HRR 2.1 & E12 : Highly stable on both Iris and Oculus. Forge Support

. It enables GPU instancing for entities even while shaders are active, which can significantly boost FPS. Version-Specific Performance & Issues

Despite the compatibility hurdles, players fight to get this working because it sits at the of visual fidelity.

Oculus is an unofficial Forge fork of Iris, designed specifically to bring Iris’s performance and shader compatibility to the Forge ecosystem. It maintains high parity with Iris, making it the premier choice for running SEUS PTGI on Forge-based modpacks.