A new Unreal Engine 5 feature added to the engine’s main development branch last week could bring substantial performance improvements to Lumen, Epic’s advanced global illumination system—and potentially make the lighting technology viable for Nintendo Switch 2 titles.
As noted by tech artist Dylan Browne on X, Epic Games has introduced Lumen Irradiance Cache, a probe-based mode designed for lower-end and portable hardware. Unlike the standard Hardware Lumen implementation, the new mode offers less occlusion detail and weaker reflections, but it’s a smart compromise that still delivers dynamic lighting effects far beyond static baked lighting solutions. A comparison video shared by Browne highlights the visual differences and demonstrates that the trade-off is more than acceptable on constrained devices.
While Lumen Irradiance Cache remains in an early state, its initial performance metrics are promising. A now-deleted GitHub commit, preserved and discussed on the ResetERA forums, suggests the new system accelerates the Lumen gather stage by approximately 2.5 times, resulting in an overall scene lighting speedup of around 1.5 times. For developers targeting energy-efficient or mobile CPUs, this could make a tangible difference.
If these improvements hold, the feature could finally open the door for Unreal Engine 5’s signature lighting to appear—albeit in scaled-down form—on Nintendo’s upcoming Switch 2 hardware. So far, even titles like Cronos: The New Dawn, built with UE5 for the next-gen handheld, have avoided Lumen due to performance concerns. The system’s heavy CPU requirements have made real-time global illumination unattainable on less powerful devices.
Currently, even Fortnite, Epic’s own flagship title, disables both Lumen and Nanite on Switch 2, underscoring the performance challenges. However, Epic’s work on the Irradiance Cache is a clear signal that optimization efforts are well underway. If successful, this lighter Lumen mode could allow developers to deliver significantly improved lighting and visual parity across platforms—even on Nintendo’s new hybrid console.
