Optimum Realism attempts to compromise performance as little as possible while still taking the visuals to a whole new level.
Game performance can be severely affected by high-resolution textures. Many such resource packs indeed take the texture resolutions to new extremes to add more details and depth.
For those players, the solution may come in the form of the Optimum Realism resource pack. For some players, seeing a resource pack that adds more depth and upscales the visuals is something worth having.
Even if for some Minecraft may seem dated in terms of graphics, there are a lot of players that enjoy it just the way it is.
