Why are Horizon textures pixelated in open zones?

Pixelated mountains ruined my ride in Rose Town. I tried a 32GB page file, which dropped FPS from 78 to 61. I used GamePP BIOS Wizard to set timings to 36-38-38-72. AIDA64 showed latency dropping from 102-115ns to 76-82ns, and VRM temps held at 58-63℃.