Minecraft randomly got laggy when using shaders?

Ok, so right off of the bat, I'm going to list my pc's specs: Dell Inspiron 560, Windows 10, Intel Core i3, 6GB of Ram. Two weeks ago I was using a GTX 460 for a GPU. With that setup, I would get about 30-40 fps while using a shaders mod, SEUS specifically. Yesterday, my oldest bro came over with his wife and two little kids and he sold me his old GPU, a GTX 660, which I installed on my pc immediately. My nephew, who I just mentioned came with him, always likes to play Minecraft while over at my house. So opened minecraft and saw it was running just as smooth as before, about 50 fps or so.

Now, the next day, or today to be more precise, I decide to get on minecraft myself. When I get on any world, whether it be local or online, I only get 10 to 15 fps with shaders on. With them off, I'm getting 80 fps. It's not the GPU as other games run great on it. What in the world would cause Minecraft to run great one day, but terribly the next? I've checked all of the settings and nothing has been changed at all from what I can see…

Some shader packs are insanely graphics intensive, just try to find a easier shader pack. Also within Minecraft change the shader settings, that impacts the game greatly.