Minecraft anyway to reduce lag when using a shader without changing the graphics to fast?

My computer used to be able to handle mods really well but now it dosent when i put shaders on it lags like crazy anyway to change it, my fps was 14 and when i pressed F11 it put the fps to 34 i cant play with a small screen and i wish to reduce lag without changing the nice looking game to shitty graphics. My settings are mostly off and i have graphics fancy which used to run fine and i have trees to defefault, ive tried putting graphics fast and trees to fancy but to no avail. I also have lagometer on and its very green yellow and purple with specs of red and orange. So yeah reduce lag without major inpact on graphics.

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