It's infrequently to see 4k resolution textures in Minecraft, and Nova photorealism is one of these texture packs. Its unimaginable resolution contributed to it being so much like real-life, and it also contributed to its performance because it's so laggy. Still, as a solution, you can try the lower versions like the 512x, and not to mention this one is entirely free in opposed to the 4k resolution, so rather than the performance difficulty, nothing is keeping you from trying it out.