No legitimate scene group releases 3DS games at 100MB. The smallest legitimate Pokémon X repack from trusted groups (like "TheTechnician" or "d0k3") is rarely below 800MB.
To run a compressed Pokémon X file, you'll need one of the following: The gold standard for PC and Android. pokemon x 3ds highly compressed download repack
"High compression" in the context of 3DS ROMs typically involves: No legitimate scene group releases 3DS games at 100MB