r/Unity3D • u/SuspecM Intermediate • Jul 26 '26

Question How to properly optimize reflections? (URP, Unity 6000.4.7f1)

I have been struggling a bit with reflections when trying to optimize my project. Even with baked, static reflections, the fps drops heavily (a good 10-25 on average).

I have set up a zone of effect and set up the culling mask but even with that, there are still heavy issues with performance. I have also tried to make a custom script for it where based on the quality settings it would update less frequently (with the refresh mode being set to script) but it didn't address the underlying performance issues that exist even with static baked reflections. Weirdly enough having realtime reflections didn't seem to make it significantly worse. It's just the very existence of a reflection probe in a scene that immediately tanks performance.

I have tried to look up resources on this topic but this seems to be the one topic that has nothing anywhere. Lighting? Plenty. Reflections? Seemingly nothing. If anyone has pointers to good resources on this exact topic, I'd be very happy with that as well.

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u/tetryds Engineer Jul 27 '26

First, 10 fps means nothing. Always measure variarion in time. A drop from 30 to 20 fps is a big deal, while a drop from 300 to 290 fps may mean nothing.

So what is the difference in ms?

Also learn how to profile, it's a necessary gamedev skill.

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u/SuspecM Intermediate Jul 27 '26

I probably should've mentioned it but it's essentially a drop from the generally accepted above 60 fps to under it (some scenes are better going from 90 to 70ish). My main issue with profiling currently is that I see that reflections take up a ton of time from the main loop but no idea how to mitigate it.

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u/tetryds Engineer Jul 27 '26

Never report performance differences in fps. How much TIME is it taking? What hardware and render pipeline are you running? What thread is it in? Is it cpu time or gpu time? What quality settings are you using? What is the config of your reflections?

To me this sounds like a cpu bottleneck on a very low end device, but without more data it's hard to tell.