Also, what is your processor? Besides RAM, Proteus really sucks up juice out of the processor! Your processor must be good at single-threaded apps as Proteus is a single-threaded application. Since there is only 1GB RAM, I'm suspecting the processor's pretty weak too. Also, when I switched display to OpenGL, I found some improvements (not sure how), but I don't think your PC comes with discrete graphics and Intel onboard graphics are nowhere near impressive (also, they can't handle OpenGL).