Nvidia's DLSS, or Deep Learning Super Sampling, allows games to look near-native to 4K (or indeed, any other) resolution while allowing the game to render at a lower resolution internally, thanks to some clever artificial intelligence machine learning wizardry. This allows games to give high frame rates and still retain most of the visual benefits of a higher resolution.
It's exclusive to RTX cards, but it does offer a nice performance bump in the games that support it. Rust is about to be added to that roster, with the update on July 1st adding the feature, that should help with performance, especially given how it struggles to run due to its somewhat poor optimization on PC.
It follows one of many updates for Rust, including Nvidia Reflex which was added last month to help reduce latency within the game. It also got a visual overhaul recently, with the graphics now looking nicer than ever. It's nice to see the game is continuing to get some great quality of life updates.
DLSS is heading to some other games soon, including Doom Eternal (alongside Ray-Tracing, which is where you're really gonna need it) and Lego Builder's Journey, both of which will be dropping later in the month.