Help Mbp early 2011 white background and slow overall performance

I have recently upgraded my macbook pro early 2011 to Sonoma and the experience is shocking. I have a white background and I can't change it, the fans are running at full blast constantly while having nothing open and overall performance is just slow, I tried everything that I know of. Reverting and installing post install patches, Reinstalling high Sierra and installed Sonoma again and I still have the same result. My specs are Cpu: 2ghz quad core Intel i7 Gpu: Amd Radeon HD 6490m 256 mb Intel HD Graphics 3000 512 mb Memory 16gb 1600 mhz DDR3 Ssd: Kingston 240gb