If the amd is soldered to the MoBo, ur stuck with it.
If not, upgrade to A9 (i just did HP G6-2237cl, dual core amd a6 to quad A8-4500M for $7+free shipping!)
If it is soldered, Ur next best upgrade is a 2nd ssd in raid0. One of the Lenovo S145 decent features, is an M.2 slot on top of a regular...