A12-9700P apu and AMD Radeon R8 m445DX with linux

Hello I bought a computer with a A12-9700P apu and AMD Radeon R8 m445DX with 2Gb Dedicated Vram on board and 16Gb ram. I need to use linux on it, preferibly ubuntu or linux mint. I only managed to install opensuse leap 42.3 and tumbleweed but it doesn't seem to work well. It is slower than my 5 years old pentium computer with 4Gb ram. I need to know why there are no official linux driver for this APU / Radeon graphics card. I am very very disappointed. It is the first time that I buy a computer with an AMD processor and up to now I had never had any issues with linux. Please help me.