Strange frame rate drop

Hey all,

I’m designing a interior scene in UE5 and realized everytime that red area appears even slightly on the player’s camera, FPS dropped from 60-70 to 40. I also noticed this only occurs when facing that area from this distance or so, when I come close to it, FPS is normal again.

I quickly imagined it was because of the curtains interacting with the wind, but even after I deleted it from the scene, the frame rate is dropping the same way.
Now I imagine if the level has some kind of stored data that needs to be reseted to “forget” the curtains that were there or something like that. Do you guys know something about it or know anything that may be causing that problem?

I don’t think it’s the red area, it’s when you have the whole room in view.

When you get close to the red area, the rest of the room is not in view.

The easiest way to find out what it is, is to just remove articles from the scene. Each time, if it makes no difference, put it back ( ctrl-z ).

Eventually you find the culprit :slight_smile:

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Thanks for the answer, it ended up being a planar reflection I placed for the bathroom’s mirror, its volume was leaking to the main area.
I had no idea a simple and small planar reflection could do this to the frame rate count o.O

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Depending (or not) on quality, planar reflection are essentially just a second scene render - so yes, their costs can halve (or worse) your frame rate…

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