“Support global clip plane for Planar Reflections” in Project Settings has a warning that it “increases BasePass triangle cost by ~15% regardless of whether planar reflections are active”.
Am I understanding it right that any and all rendering in this project will take a performance hit, just from enabling this option - even if no Planar Reflection actor is present/active? If so, how severe can it get? I found plenty of information about optimizing Planar Reflection actor settings, but nothing describing this base cost.
For exact numbers you’ll need to profile but it was fast enough that Epic has shipped it for VR in Robo Recall 7-8 years ago which IIRC had to run on a GTX 970 at 90fps in both eyes. If you are curious they did a livestream where they discussed how they set this up to meet the performance requirements: https://www.youtube.com/live/3Yx9IEOc5s4?si=gkBfiy3RulTI_QMs&t=1475
Worth mentioning that (at least the last time I checked) planar reflections do not work with Lumen and should not be used together.