I think your CPU is the issue here. NSMB isn't a particularly demanding game, but 1.8GHz is slow for Dolphin emulation. I don't believe your GPU is the problem, as people have gotten away with less (like the Intel HD 3000). There should be a way to overclock your CPU; using AMD's TurboCore, you can automatically get 2.5GHz. I think Notebook Check has some info on your CPU, though I have no idea how you would activate TurboCore. Check you BIOS for more information on that.
Also, be careful when overclocking laptops. Temperature and cooling are big concerns. I don't think Real Temp works with AMD's chips, but Core Temp should do just fine if you want to monitor your CPU's temperatures.
Also, be careful when overclocking laptops. Temperature and cooling are big concerns. I don't think Real Temp works with AMD's chips, but Core Temp should do just fine if you want to monitor your CPU's temperatures.