Why my minecraft is so extreme lag when I installed Shaders mod?

My Minecraft 1.7.5 has extreme lag! When I installed shaders mod. It's not lagging when I'm not loading worlds. When I select Shaderspack my minecraft is lagging then freeze. I'm on Windows Vista Home Premium. My Java Version is Java 7 Update 55. My minecraft is very smooth when I uninstalled Shaders mod and Shadersmodcore

That clearly means the Mod is messing with the game program and causing it not to work. THis could be because the Mod simply isn't compatible with the version you're playing (but is try9ing to run anyway) or it might just be a badly programmed Mod.

You're computer is not powerful enough for shaders if it has that much lag. Imagine if nonmodded minecraft represented a game like Super Mario bros. And Shaders Minecraft represented Battlefield 3. Just because a computer can run a game like minecraft, doesn't mean you should try upping the graphics unless you know your computer can handle it. In this case, you didn't know and lacked knowledge of your PC's power.