How do reflection probes influence performance, and how would you optimize their use?

• A. They always improve rendering performance.
• B. Reflection probes have no impact on performance because they are cached.
• C. They can be costly if many are active; optimize by limiting number, using cubemap updates sparingly, and using proxy/reflection textures where feasible.
• D. They are automatically disabled on mobile devices.

Answer: (D)

Reflection probes control how shiny surfaces reflect their surroundings by capturing the scene into cubemaps. If a probe is set to real-time, it updates that cubemap every frame to reflect moving objects, which can be very expensive. The more probes you have and the higher their resolution, the more hardware work is required, and you’ll see a bigger hit on frame rate, especially on lower-end hardware or mobile.

To optimize their use, limit how many probes are active and where they’re placed so they cover only the most important reflective areas. Use baked probes for static environments where reflections don’t need to update every frame. When real-time updates are necessary, reduce how often they update (or disable real-time updates entirely for probes that don’t need dynamic reflections), and lower the cubemap resolution to cut the rendering cost. If possible, replace or supplement probes with cheaper options like proxy textures or simplified reflection textures for certain surfaces. Also consider alternatives like planar reflections for bodies of water or highly reflective surfaces when a full cube-map approach is too costly.

On mobile, you’re not automatically guaranteed to have reflection probes disabled; you typically manage this through your quality settings, choosing baked or lower-resolution probes and turning off realtime updates where performance is tight.