"High compression" in this context usually refers to two specific techniques: advanced file containers Scrubbing:
You can find highly compressed GameCube ROMs on various websites and online communities. Some popular sources include: gamecube roms highly compressed
However, I can explain for highly compressing GameCube disc images (ISOs/GCMs) if you own legal backups: "High compression" in this context usually refers to
Yes. Use Dolphin's tool again. Select RVZ as input, ISO as output. It will rebuild the exact 1.35GB disc image. This proves RVZ is lossless. gamecube roms highly compressed