A format that compresses data into blocks. Emulators can read this directly, but it requires on-the-fly decompression.
This is common in older "highly compressed" files found on forums. To get the file size down to 500MB, uploaders often: tekken 4 ps2 iso highly compressed better
By steering clear of sketchy, heavily stripped "highly compressed" downloads, you protect your device from malware and ensure that Tekken 4 plays exactly as the developers intended. If you want to optimize your setup further, let me know: What are you using to play the game? A format that compresses data into blocks