Cheapest option since you have a dedicated gpu is replace that molasses filled APU with an Athlon 860k Quad Core. That's at least a simple move from 2.5GHz to 3.7GHz, not to mention the large discrepancy in Lcache, which will speed things up quite a bit. The 860k is also overclockable, so depending on your mobo's ability, and your cpu coolers ability, you could at least minimize the bottleneck as much as physically possible on the FM2+ platform.