Are you playing vanilla 1.12.2, or are you running a specific (like RLCraft)?
Realistic lighting and water at a fraction of the hardware cost. 4. SEUS (Sonic Ether’s Unbelievable Shaders)
: Exceptionally stable and highly customizable. It washes the overworld in a warm, golden sunlight and features wavy grass, leaves, and beautifully illuminated night skies. It offers multiple versions (Lite to Extreme) to match your hardware power. minecraft 1.12 2 shaders
Shadows are the main cause of lag. Disabling them in the shader options can gain you significant FPS.
9/10
Entities and blocks cast realistic shadows based on the sun's position. Prerequisites: Getting Ready for Shaders
Are you aiming for or highest visual quality ? Are you playing vanilla 1
One distinct characteristic of 1.12.2 shaders was the heavy reliance on bloom (light glow). SEUS v10, for example, had a very specific washed-out, dreamlike bloom that made sand look like plastic. While visually distinct, this often washed out dark colors, a problem that later shader versions in 1.14+ attempted to fix.