Performance issues with cycles render

guys having an issue with render times was hoping someone might give me so advice.
I have a dell inspirion 3656 desktop the graphics says AMD Radeon™ R9 360 2GB DDR5.
I followed the video setting up for cpu or gpu and the quickest time I get rendering the BMW image is 12 mins. would anyone know if this might be because of the computer or the type of graphics card I am using.
Sorry this is so vague but all this is new to me.
thanks