I use a solid 2 year old Toshiba laptop. i5 M450 @ 2.4Ghz, 4GB RAM, GeForce GT 330M, 500GB hard drive. Runs 60+ FPS vanila and about 40+ modded with Optifine, but as soon as I start having a lot of stuff going on (quarry, Item sorter, various logic timers, etc) it slows down to an unplayable 10...