The mention of Unreal Engine 4 (UE) often brings to mind impressive-looking demos that elicit more than a fair share of oohs and aahs. Epic Games isn't resting on its laurels, and it's just released UE 4.15 with support for alternate frame rendering (AFR) on Nvidia SLI configurations and experimental support for HDR output, along with a Kardashian buttload of performance optimizations and developer-oriented improvements.
High-end PC enthusiasts with multiple Nvidia cards in SLI will be happy to know that games built using UE 4.15 can take advantage of alternate frame rendering, meaning they'll likely see a hefty performance boost. According to Epic, "the largest improvement comes from the renderer copying inter-frame dependencies between GPUs as early as possible." Developers will still need to work with Nvidia and test their games on this scenario, though.
Those with fancy HDR TVs or monitors are possibly saddened by the lack of HDR content out there. Epic is aware, as it's just added experimental HDR support to UE 4.15. The engine can currently output HDR content on Nvidia cards under the Direct3D 11 API or on devices that support Apple's Metal graphics API. The company says that there are rendering paths for 1000-nit and 2000-nit displays, and that it'll be adding support for more devices and configurations in the future.
That's not all the good news for gamers. The new version of UE comes with a spankin' new Texture Streaming system, which purports to "reduce CPU usage, memory usage, and load times while eliminating low resolution artifacts." More to the point, Epic says that developers can look forward to an up-to-40% reduction in texture memory usage, faster game load times, and a near-elimination of texture processing-related stalls. Owners of graphics cards with 2GB or 4GB of VRAM should be particularly happy. Maybe even Bethesda can take a hint on the texture size reduction topic, dunno.
There are a few other minor-but-important improvements. Windows games built on UE can now use non-XInput flight sticks and steering wheels, welcome news for simulator buffs everywhere. Developers can now target Nintendo Switch and Linux ARM64 platforms. Mobile VR games can take advantage of Monoscopic Far Field Rendering. Check out Epic's announcement for the nitty-gritty, especially if you wrangle game code or assets for a living.