That 36 MB/s has to be sustained from PSRAM to the LCD DMA, while the CPU (and LovyanGFX, used for graphics) are also writing ...
PlatformIO library LVGL Drivers for Sunton Smart display boards (CYD Cheap Yellow Display). This library supports these boards without any effort. ESP32-2432S024N/R/C, ESP32-2432S028R/C, ...