In fact, you would need to get something close to 200 FPS if you wanted to use the Shaders Mod and still get a decent framerate with all of the settings turned up to their maximum values. The Shaders Mod can have such a strong effect on Minecraft that the FPS may be seriously reduced, even for players who normally get a nice 60+ FPS when playing the game normally.
There are actually normal maps and specular maps to consider too, because the Shaders Mod allows you to change the appearance of your Minecraft world in some unexpected ways by modifying these aspects of the game, which you may not have even realized existed without this mod. This mod, authored by karyonix, is actually a fine shader mod that adds a special shadow map to the world to complement the lightmap which is already there.
There are so many shader packs and mods out there that the Shaders Mod might easily be overlooked by players who search using more specific terms.
