Cause: Default core is "DuckStation" (heavy). Fix: Press A/B on the game -> Edit Metadata -> Per system advanced config -> Emulator Core -> Switch to PCSX-ReARMed.

Because EmuELEC 4.3 relies on older Libretro cores, you need compatible ROM sets.

In Game Settings, adjust the Emulator selection:

Use balenaEtcher to write the .img.gz directly to your SD card. Etcher will automatically decompress it.

The default skin (a modified version of the popular "Art Book" theme) is gorgeous.