Hi,
Follow the following tutorial for allocating more memory to Minecraft: http://www.minecraftforum.net/topic/139 ... minecraft/

Go into Control Panel > Programs > Java > Java > View > -XmxMAXRAM -XmsMINRAM > Ok > Ok
MAXRAM = Maximum RAm and MINRAM = Minimumram

tried using that program but it black screened my mc

ill actually answer your question . You could use Magic Launcher.

Shaders mod could make much lag too

hey mate im using GLSL Shaders mod and i am using moartex tp i thinks its only 64x64 obviously i have optifine but it doesnt really help but i am more looking to add more memory like instead of 258mb of ram dedicated i want more

There is lots of mods that you can get to fine-tune your performance, like Optifine n' stuff, and it also depends on the texture pack you use as well. If you are using a high definition texture pack (128 x 128, 256 x 256, etc.) it could also lag the game if you haven't patched it good enough.

Hope this helps!