why low fps?

Solution
First, you've not specified your resolution and the settings you are using, however most likely it is because of your CPU (i.e. the CPU portion of your APU). It is quite weak by modern standards, so you will need to lower those settings that reduce the number of objects on screen (e.g. draw distance). Your graphics card is appropriate for that CPU, but you may need to reduce AA and/or image complexity.
First, you've not specified your resolution and the settings you are using, however most likely it is because of your CPU (i.e. the CPU portion of your APU). It is quite weak by modern standards, so you will need to lower those settings that reduce the number of objects on screen (e.g. draw distance). Your graphics card is appropriate for that CPU, but you may need to reduce AA and/or image complexity.
 
Solution