Hardly worth building a whole new PC, it's obvious that it's CPU dependent as if you're running a server you'll quickly notice that it only chokes up 1 core, therefore clock speed is the way forward.
The other cores are used up on databases related to it (plugins etc)
Source: Being co-owner of a former popular minecraft server.
Trail it seems you have a cronic issue about not reading the whole thread above your post.
Problem SOLVED and now my Minecraft runs smothly at 40 fps Normal +98 or Far render ( alltho i prefer short because of the realistic fog).Also i will give you my whole specs just to see that Minecraft isnt about hardware its just about configuration and do remember FPS over 30 is not detected by the human eyes...so is no point having 200 fps.Also if you refer to Page file alocation...higher than 2x your Ram will actualy cause your Pc to run even slower.
I play Multiplayer and the only drawback is that most of my Piston Contraptions turn into Lag Generator Machines when you are near and its on and thats because my light house has over 40 pistons.