According to your testing, does the issue occur with ONLY Immersive Portals mod and Farbic API?

Yes

Describe the issue

I get serious FPS performance issues when looking at a portal that's linked with immersive. I'm running a 3090 kingpin, so this shouldn't be an issue for me. The frametimes increase significantly when looking at a portal, too. My frames will hover around 30FPS when looking at one.

I know that we're technically rendering two dimensions when this is in view, but there shouldn't be such a performance loss. Some performance loss is expected.

Post the log here

No response

I've tried with shaders, and without. Both have the same effect. I'm playing in 4k, if that's any help.

Are you using shaders?

What's your frames when not looking at a portal?

A solid 60FPS, frame times are nearing 20ms IIRC. I use vsync, can test without if needed.

Try without vsync, also as a general rule of thumb, don't use vsync like ever

Vsync improves choppy behavior on most if not all games I play on, to be fair.

240FPS without vsync and not looking at portal, 40-50FPS when looking at portal.

Jeez, idk what is wrong with your game, I have a GTX 1060 and my fps doesn't dip like that

Will having sodium and iris installed affect FPS by that much? I mean they're both designed to increase perf and are included in pretty much every modpack, but there's "incompat" messages with them installed.

Also, are there settings I can change to limit rendering distance on the other side of the portal? Maybe I can tweak it so there's only a few chunks loaded until I actually pass through the portal...

Will having sodium and iris installed affect FPS by that much? I mean they're both designed to increase perf and are included in pretty much every modpack, but there's "incompat" messages with them installed.

Wdym there's incompat messages

Oh you're fine you won't really notice anything, just click disable warnings

Alright. What can be done to improve the FPS here? Anything from the mod's end?

I see that there's a distance to portal render option. If it were possible, it would be cool to see an option that controls the render distance on the other side of the portal.

What's your render distance? Have you tried 12?

I cannot reproduce this issue. Does this issue occur in every world or only a specific world? Does this issue occur with render distance 12? Have you changed other config related with rendering? Have you changed any option of immptl (if so try to reset all the settings)? What's your screen resolution?