He claims that, at max, you could see up to a 5fps drop in some areas, but that seems well worth it considering the upgrade in visual fidelity. The mod author states that using anything from a GTX 970/AMD R9 290X up should result in no hit to performance. Most impressive of all is the claim that these improvements should have little to no impact on performance.
The improvements there are easy to see, especially in NPC armors. Beyond just improving environmental textures, this mod also targets The Witcher 3‘s character models. Old, murky textures are brought to full detail without changing the original intent or feel. Halk’s mission to improve all the visuals in the game is lofty, but it’s hard to argue with the results. As the preview video shows, the mod takes the older textures and dramatically increases their sharpness. Most of the textures improved here have had their quality doubled from their original level of detail. This ambitious mod, created by Nexus user Halk Hogan, sets out to revamp all the textures in the game, bringing the modern classic into the 4k age. The Witcher 3 HD Reworked Project aims to correct for that. A little over four years later, however, technology has caught up and left Witcher 3‘s graphics behind.
Back then, even the beefiest of systems struggled to run it at max settings. The Witcher 3: Wild Hunt was an incredibly impressive game in all regards when it came out in 2015.